I am making a project. It draws concentric circles in android canvas. When the user drags the screen, all the circles move accordingly. Here is my code so far.
activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:background="#android:color/white">
<RelativeLayout
android:id="#+id/scrollableSpace"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentRight="true"
android:layout_alignParentBottom="true"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true">
<project.myProject.DrawOrbit
android:id="#+id/orbitsRegion"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentRight="true"
android:layout_alignParentBottom="true"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true" />
</RelativeLayout>
</RelativeLayout>
MainActivity.java
public class MainActivity extends AppCompatActivity implements View.OnTouchListener
{
PointF center;
center.x=500;center.y=500;
float radius[]={100,200,300,400,500};
DrawOrbit orbit;
int startX=0,startY=0,currentX=0,currentY=0;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RelativeLayout layout=(RelativeLayout)findViewById(R.id.scrollableSpace);
orbit.draw(center,radius);
layout.setOnTouchListener(this);
}
#Override
public boolean onTouch(View v, MotionEvent motionEvent)
{
final int action= motionEvent.getAction();
switch(action & MotionEvent.ACTION_MASK)
{
case MotionEvent.ACTION_DOWN:
{
startX=(int)motionEvent.getRawX();
startY=(int)motionEvent.getRawY();
break;
}
case MotionEvent.ACTION_MOVE:
{
currentX=(int)motionEvent.getRawX();
currentY=(int)motionEvent.getRawY();
float diffX=currentX-startX;
float diffY=currentY-startY;
startX=currentX;
startY=currentY;
center.x+=diffX;
center.y+=diffY;
orbit.draw(center,radius);
break;
}
}
return true;
}
}
DrawOrbit.java
public class DrawOrbit extends View
{
PointF center;
float radius[];
public DrawOrbit(Context context) {
super(context);
}
public DrawOrbit(Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
}
public DrawOrbit(Context context, #Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
paint.setColor(Color.BLACK);
paint.setStrokeWidth(2);
paint.setStyle(Paint.Style.STROKE);
int len=radius.length;
for(int a=0;a<len;a++)
{
canvas.drawCircle(center.x,center.y,radius[a],paint);
}
}
public void draw(PointF center, float radius[])
{
this.center=center;
this.radius=radius;
invalidate();
requestLayout();
}
}
What I want to do is that the circles should appear one by one. First the inner most circle then the next one after some delay then the next and so on. The same effect should be seen when the screen is dragged. How can I achieve this? Any help will be appreciated.
What you're looking for is a timeout. I'd suggest creating a new thread to draw everything, and start by drawing the first circle, have the method look like this:
public void drawCircle() {
//Draw logic
TimeUnit.SECONDS.sleep(3);
drawNextCircle();
}
//Assuming on java 1.8+
Thread thread = new Thread() => {
drawCircle();
}
What this will do is have the thread sleep for 3 seconds, and then continue normal operation after the time period is up. You can change it to other measurements of time such as TimeUnit.MILLISECONDS or TimeUnit.MINUTES as well.
edit: You likely won't want this in your main thread, as it will stop the ENTIRE application from working for however long you put the thread on timeout, so it's almost essential for this to work that you put it in a separate thread.
edit 2: It would make more sense to add a separate util method to timeout and then call another method via reflection than the above code, but the same code would be needed.
Figured out the answer to my own question. I had to use a Handler, multiplied the delay with the for-loop variable and made 1 then 2 then so on.. circles to get the desired effect. Here is the code.
MainActivity.java
public class MainActivity extends AppCompatActivity implements View.OnTouchListener
{
PointF center;
center.x=500;center.y=500;
float radius[]={100,200,300,400,500};
DrawOrbit orbit;
int startX=0,startY=0,currentX=0,currentY=0;
Handler handler1 = new Handler();
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RelativeLayout layout=(RelativeLayout)findViewById(R.id.scrollableSpace);
for (int a = 0; a<radius.length ;a++)
{
final int index=a;
handler1.postDelayed(new Runnable() {
#Override
public void run() {
orbit.draw(center,radius,index);
}
}, 300 * a);
}
layout.setOnTouchListener(this);
}
#Override
public boolean onTouch(View v, MotionEvent motionEvent)
{
final int action= motionEvent.getAction();
switch(action & MotionEvent.ACTION_MASK)
{
case MotionEvent.ACTION_DOWN:
{
startX=(int)motionEvent.getRawX();
startY=(int)motionEvent.getRawY();
break;
}
case MotionEvent.ACTION_MOVE:
{
currentX=(int)motionEvent.getRawX();
currentY=(int)motionEvent.getRawY();
float diffX=currentX-startX;
float diffY=currentY-startY;
startX=currentX;
startY=currentY;
center.x+=diffX;
center.y+=diffY;
break;
}
case MotionEvent.ACTION_UP:
{
for (int a = 0; a<radius.length ;a++)
{
final int index=a;
handler1.postDelayed(new Runnable() {
#Override
public void run() {
orbit.draw(center,radius,index);
}
}, 300 * a);
}
break;
}
}
return true;
}
}
DrawOrbit.java
public class DrawOrbit extends View
{
PointF center;
float radius[];
int index;
public DrawOrbit(Context context) {
super(context);
}
public DrawOrbit(Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
}
public DrawOrbit(Context context, #Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#Override
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
paint.setColor(Color.BLACK);
paint.setStrokeWidth(2);
paint.setStyle(Paint.Style.STROKE);
int len=radius.length;
for(int a=0;a<index;a++)
{
canvas.drawCircle(center.x,center.y,radius[a],paint);
}
}
public void draw(PointF center, float radius[],int index)
{
this.center=center;
this.radius=radius;
this.index=index;
invalidate();
requestLayout();
}
}
Related
I am drawing on android.graphics.Canvas using android.graphics.Path. I want to allow the user to draw using a range of colors and stroke widths, however, whenever the color or stroke width is changed, everything is re-drawn using the new color or stroke width. How can I fix this?
xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/activity_main"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:id="#+id/btnW10"
android:layout_margin="3sp"
android:layout_weight="1"
android:text="Width10"/>
<Button
android:id="#+id/btnW40"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="3sp"
android:layout_weight="1"
android:text="Width40"/>
<Button
android:id="#+id/btnW70"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="3sp"
android:layout_weight="1"
android:text="Width70"/>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="20dp"></LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="3sp"
android:layout_weight="1"
android:id="#+id/btnBlue"
android:text="Blue"/>
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="3sp"
android:layout_weight="1"
android:id="#+id/btnRed"
android:text="Red"/>
<Button
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_margin="3sp"
android:layout_weight="1"
android:id="#+id/btnGreen"
android:text="Green"/>
</LinearLayout>
<com.vladislav.canvaswc.DrawLine
android:id="#+id/drwLine"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</LinearLayout>
main.java:
public class MainActivity extends AppCompatActivity implements View.OnClickListener
{
DrawLine dr;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnB=(Button) findViewById(R.id.btnBlue);
Button btnG=(Button) findViewById(R.id.btnGreen);
Button btnR=(Button) findViewById(R.id.btnRed);
Button btnW10=(Button) findViewById(R.id.btnW10);
Button btnW40=(Button) findViewById(R.id.btnW40);
Button btnW70=(Button) findViewById(R.id.btnW70);
dr =(DrawLine) findViewById(R.id.drwLine);
btnB.setOnClickListener(this);
btnG.setOnClickListener(this);
btnR.setOnClickListener(this);
btnW10.setOnClickListener(this);
btnW40.setOnClickListener(this);
btnW70.setOnClickListener(this);
}
#Override
public void onClick(View v) {
switch(v.getId())
{
case R.id.btnBlue : dr.changeColor(Color.BLUE);break;
case R.id.btnGreen : dr.changeColor(Color.GREEN);break;
case R.id.btnRed : dr.changeColor(Color.RED);break;
case R.id.btnW10 : dr.changeWidth(10f);break;
case R.id.btnW40 : dr.changeWidth(40f);break;
case R.id.btnW70 : dr.changeWidth(70f);break;
}
}
}
drawline.java ChangeWidthColor its my interface with 2 methods changeColor()
and changeWidth()
public class DrawLine extends View implements ChangeWidthColor {
private Paint paint = new Paint();
private Path path = new Path();
public float x;
public float y;
public DrawLine(Context context) {
super(context);
init(context);
}
public DrawLine(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public DrawLine(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public void init(Context context) {
//paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.MITER);
//paint.setStrokeWidth(5f);
}
#Override
public void changeColor(int color) {
paint.setColor(color);
}
#Override
public void changeWidth(float width) {
paint.setStrokeWidth(width);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawPath(path,paint);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
x= event.getX();
y= event.getY();
path.moveTo(x, y);
break;
case MotionEvent.ACTION_MOVE:
x= event.getX();
y= event.getY();
path.lineTo(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
invalidate();
break;
}
invalidate();
return true;
}
}
This solution maintains a List of Path objects and a List of Integers for storing colors. These Lists are in parallel - 1 entry in each list for a Path and color pair. onDraw iterates these Lists, drawing each Path with the corresponding color.
Each time the user clicks to change the color, a new Path is created. ACTION_DOWN and ACTION_MOVE call moveTo(x,y) and lineTo(x,y) on the path, and ACTION_UP causes the Path and current color to be added to the lists.
Note: I have not implemented a solution for stroke width, however, you should be able to follow the example and add this yourself.
public class DrawLine extends View {
private Path path = new Path();
private Paint paint = new Paint();
private int currentColor = Color.BLACK;
private List<Path> paths = new ArrayList<Path>();
private List<Integer> colors = new ArrayList<Integer>();
private float x;
private float y;
public DrawLine(Context context) {
super(context);
init(context);
}
public DrawLine(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public DrawLine(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public void init(Context context) {
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.MITER);
paint.setColor(currentColor);
}
public void changeColor(int color) {
currentColor = color;
path = new Path();
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (int x = 0; x < paths.size(); x++) {
paint.setColor(colors.get(x));
canvas.drawPath(paths.get(x), paint);
}
}
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
x = event.getX();
y = event.getY();
path.moveTo(x, y);
break;
case MotionEvent.ACTION_MOVE:
x = event.getX();
y = event.getY();
path.lineTo(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
paths.add(path);
colors.add(currentColor);
invalidate();
break;
}
invalidate();
return true;
}
}
`
public class DrawLine extends View implements ChangeWidthColor {
private Path path = new Path();
private Paint paint = new Paint();
private int currentColor = Color.BLACK;
private float width = 1f;
public float x;
public float y;
private LinkedList<Integer> color = new LinkedList<Integer>();
private LinkedList<Float> widthSize = new LinkedList<Float>();
private LinkedList<Path> paths = new LinkedList<Path>();
public DrawLine(Context context) {
super(context);
init(context);
}
public DrawLine(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}
public DrawLine(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
public void init(Context context) {
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.MITER);
paint.setColor(currentColor);
paint.setStrokeWidth(5f);
}
#Override
public void changeColor(int color) {
currentColor = color;
path = new Path();
}
#Override
public void changeWidth(float width) {
this.width = width;
path = new Path();
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (int i = 0; i < paths.size(); i++) {
paint.setStrokeWidth(widthSize.get(i));
paint.setColor(color.get(i));
canvas.drawPath(paths.get(i), paint);
}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
x = event.getX();
y = event.getY();
path.moveTo(x, y);
break;
case MotionEvent.ACTION_MOVE:
x = event.getX();
y = event.getY();
path.lineTo(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
color.add(currentColor);
paths.add(path);
widthSize.add(width);
break;
default:
return false;
}
invalidate();
return true;
}
}
you need to call invalidate() inside your custom view whenever you are modifying something related to UI. so updated methods will be:
#Override
public void changeColor(int color) {
paint.setColor(color);
invalidate();
}
#Override
public void changeWidth(float width) {
paint.setStrokeWidth(width);
invalidate();
}
I put together a TextView class utilizing some different suggestions I've seen and wrote this class to display a TextView inside of a circle. The circle comes out great, but the text appears slightly above the center of the circle.
I can't figure out what's causing this. Here's my code:
CircularTextView
public class CircularTextView extends AppCompatTextView {
private ShapeDrawable backgroundDrawable;
private OvalShape ovalShape;
private int backgroundColor;
public CircularTextView(Context context) {
super(context);
backgroundColor = ContextCompat.getColor(context, R.color.color_circle_test_solid);
allocateShapes();
}
public CircularTextView(Context context, AttributeSet attrs) {
super(context, attrs);
backgroundColor = ContextCompat.getColor(context, R.color.color_circle_test_solid);
allocateShapes();
}
public CircularTextView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
backgroundColor = ContextCompat.getColor(context, R.color.color_circle_test_solid);
allocateShapes();
}
//Source https://stackoverflow.com/questions/25203501/android-creating-a-circular-textview/34685568#34685568
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int h = this.getMeasuredHeight();
int w = this.getMeasuredWidth();
int r = Math.max(w, h);
setMeasuredDimension(r, r);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
backgroundDrawable.setShape(ovalShape);
backgroundDrawable.getPaint().setColor(backgroundColor);
setBackground(backgroundDrawable);
}
private void allocateShapes(){
backgroundDrawable = new ShapeDrawable();
ovalShape = new OvalShape();
}
public void setBackgroundColor(int color){
backgroundColor = color;
invalidate();
}
}
TestCircleTextViewActivity
public final class TestCircleTextViewActivity extends BaseActivity {
#BindView(R.id.circle_text)
CircularTextView circleText;
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test_circular_textview);
ButterKnife.bind(this);
int circleColor = ContextCompat.getColor(this, R.color.color_circle_test_solid);
circleText.setBackgroundColor(circleColor);
}
}
activity_test_circular_textview.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.thinkbubble.app.ui.view.CircularTextView
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:id="#+id/circle_text"
android:layout_gravity="center"
android:layout_centerInParent="true"
android:padding="4dp"
android:text="Keyword">
</com.thinkbubble.app.ui.view.CircularTextView>
</RelativeLayout>
Use android:gravity="center" for you TextView to make text center in circle
I have a problem. I have my own scrollview, but it doesn't work. The scrollbar appears, but when I try to use it doesn't work. I have tried a lot of things, but none work. The code is:
#SuppressLint("ClickableViewAccessibility") public class myScrollView extends ScrollView {
private boolean enableScrolling = true;
public boolean isEnableScrolling() {
return enableScrolling;
}
public void setEnableScrolling(boolean enableScrolling) {
this.enableScrolling = enableScrolling;
}
public myScrollView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public myScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public myScrollView(Context context) {
super(context);
}
#Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
if (isEnableScrolling()) {
return super.onInterceptTouchEvent(ev);
} else {
return false;
}
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
if (isEnableScrolling()) {
return super.onInterceptTouchEvent(ev);
} else {
return false;
}
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidth(), getMeasuredHeight());
}
}
Inside of this scroll, I have a relativeLayout and inside of this a View. In the View I draw some bitmaps. They number more than it can display the screen.
The XML is:
<com.edjume.myScrollView
android:id="#+id/scroll_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/table">
<RelativeLayout
android:id="#+id/table"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
</RelativeLayout>
</com.edjume.myScrollView>
And in the activity I use:
RelativeLayout ll = (RelativeLayout) findViewById(R.id.table);
ll.addView(new Table(this));
And finally, in my View (Table) has a OnDraw() and a onTouchEvent(). In the onTouchEvent I use the options ACTION_DOWN, ACTION_MOVE and ACTION_UP.
I believe
#Override
public boolean onTouchEvent(MotionEvent ev) {
if (isEnableScrolling()) {
return super.onInterceptTouchEvent(ev);
} else {
return false;
}
}
should be:
#Override
public boolean onTouchEvent(MotionEvent ev) {
if (isEnableScrolling()) {
return super.onTouchEvent(ev);
} else {
return false;
}
}
I'm trying to draw some shapes onto a SurfaceView from within a thread, but nothing is being rendered to the screen. I've looked at similar questions by people having the same problem, but none of the answers have led me to a solution, suggesting a different cause in my particular case.
I've created a simplified version of my code to demonstrate the problem. Rendering is handled by the RenderingTestView class, which implements a custom view derived from SurfaceView. The rendering thread is implemented as a Runnable inside RenderingTestView:
package com.example.renderingtest.app;
import android.content.Context;
import android.graphics.*;
import android.os.Build;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class RenderingTestView extends SurfaceView {
private SurfaceHolder holder;
private Paint paint;
private boolean surfaceCreated = false;
private Thread videoThread;
public RenderingTestView(Context context) {
super(context);
init_view(context);
}
public RenderingTestView(Context context, AttributeSet attrs) {
super(context, attrs);
init_view(context);
}
public RenderingTestView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init_view(context);
}
private void init_view(Context context)
{
if (Build.VERSION.SDK_INT >= 11)
setLayerType(android.view.View.LAYER_TYPE_SOFTWARE, null);
paint = new Paint();
paint.setColor(Color.RED);
holder = getHolder();
holder.addCallback(new SurfaceHolder.Callback() {
#Override
public void surfaceCreated(SurfaceHolder holder) {
surfaceCreated = true;
videoThread = new Thread(videoRunnable);
videoThread.start();
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// do nothing
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
surfaceCreated = false;
}
});
}
private Runnable videoRunnable = new Runnable() {
#Override
public void run() {
Thread.currentThread().setPriority(Thread.NORM_PRIORITY);
while (true) {
if (!surfaceCreated || !holder.getSurface().isValid())
continue;
Canvas c = holder.lockCanvas(null);
try {
synchronized (holder) {
if (c != null)
Draw(c);
}
}
finally {
if (c != null)
holder.unlockCanvasAndPost(c);
}
}
}
};
protected void Draw(Canvas canvas)
{
canvas.drawCircle(0, 0, 100, paint);
}
}
Placing a breakpoint inside Draw() confirms that it's being called successfully.
The layout file looks like this:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:paddingBottom="#dimen/activity_vertical_margin"
tools:context="com.example.renderingtest.app.RenderingTest" android:background="#000000">
<com.example.renderingtest.app.RenderingTest
android:id="#+id/renderingTestView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" android:layout_alignParentTop="true"/>
</RelativeLayout>
Overriding onDraw() in RenderingTestView, like this:
#Override
public void onDraw(Canvas canvas)
{
super.onDraw(canvas);
Draw(canvas);
}
... and calling setWillNotDraw(false) inside init_view() does in fact produce the desired output, but I want to render from inside the Runnable rather than wait for invalidate() to produce a call to onDraw().
After further testing, I've discovered the problem is caused by the following code:
if (Build.VERSION.SDK_INT >= 11)
setLayerType(android.view.View.LAYER_TYPE_SOFTWARE, null);
It turns out calling setLayerType() as above somehow prevents SurfaceView from rendering anything onto the Canvas, and is in any case unnecessary since SurfaceView rendering is always performed in software. When first testing my draw calls I was using a regular View rather than a SurfaceView, and the offending lines were carried over from that.
I found this really useful code that allows me to scale and move a bitmap and I've been trying to find a way to use this code in my app. I don't really understand the way the class is being used (self taught java coder, so I may be missing some basics here). I basically want to be able to open up gallery and pick a file which can be used by this code. I can do all this with a standard ImageView but with an ImageView I'm unable to scale/move.
The main class, and it simply uses the touchexampleview class to place the image on screen, and the touchexampleview class contains a line which loads a default image.
mIcon = context.getResources().getDrawable(R.drawable.ic_launcher);
I could work out how to change this in the class but I want to be able to do this dynamically and be user driven.
Here is the main class.
public class TouchExampleActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
TouchExampleView view = new TouchExampleView(this);
view.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT));
setContentView(view);
}
}
and the touchexampleview class
public class TouchExampleView extends View {
private Drawable mIcon;
private float mPosX;
private float mPosY;
private VersionedGestureDetector mDetector;
private float mScaleFactor = 1.f;
public TouchExampleView(Context context) {
this(context, null, 0);
}
public TouchExampleView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public TouchExampleView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mIcon = context.getResources().getDrawable(R.drawable.ic_launcher);
mIcon.setBounds(0, 0, mIcon.getIntrinsicWidth(), mIcon.getIntrinsicHeight());
mDetector = VersionedGestureDetector.newInstance(context, new GestureCallback());
}
#Override
public boolean onTouchEvent(MotionEvent ev) {
mDetector.onTouchEvent(ev);
return true;
}
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
canvas.translate(mPosX, mPosY);
canvas.scale(mScaleFactor, mScaleFactor);
mIcon.draw(canvas);
canvas.restore();
}
private class GestureCallback implements VersionedGestureDetector.OnGestureListener {
public void onDrag(float dx, float dy) {
mPosX += dx;
mPosY += dy;
invalidate();
}
public void onScale(float scaleFactor) {
mScaleFactor *= scaleFactor;
// Don't let the object get too small or too large.
mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));
invalidate();
}
}
}
I am not sure, but is this what you are looking for?
imageSpot.setImageResource(R.drawable.myImage);