I have a simple app that draws a line as you move your finger around the screen.
I want to change it so instead of it drawing behind the finger, a circle follows directly below where you have touched. As you move your finger along the screen the circle should follow. It should not leave a path behind it.
The circle should appear where the finger is when the screen is touched and disappear when the finger is lifted.
MainActivity:
package com.example.dot2;
import android.app.Activity;
import android.os.Bundle;
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SingleTouchEventListener(this, null));
}
}
SingleTouchEventListener:
package com.example.dot2;
import...
public class SingleTouchEventListener extends View {
private Paint paint = new Paint();
private Path path = new Path();
private Paint mPaint;
public SingleTouchEventListener(Context context, AttributeSet attrs) {
super(context, attrs);
paint.setAntiAlias(true);
paint.setStrokeWidth(6f);
paint.setColor(Color.RED);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawPath(path, paint);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = event.getX();
float eventY = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
path.moveTo(eventX, eventY);
return true;
case MotionEvent.ACTION_MOVE:
path.lineTo(eventX, eventY);
break;
case MotionEvent.ACTION_UP:
// nothing to do
break;
default:
return false;
}
// Schedules a repaint.
invalidate();
return true;
}
}
Thanks
I actually found code which did most of what I needed and added the rest...
Here's the code:
public class drawingView extends View implements OnTouchListener{
static int x,y,r=255,g=255,b=255;
final static int radius=30;
Paint paint;
public drawingView(Context context)
{
super(context);
paint=new Paint();
paint.setAntiAlias(true);
paint.setARGB(255, r, g, b);
setFocusable(true);
this.setOnTouchListener(this);
}
public void onDraw(Canvas canvas)
{
paint.setARGB(255, r, g, b);
//drawing the circle
canvas.drawCircle(x,y,radius,paint);
}
public boolean onTouch(View view,MotionEvent event)
{
x=(int)event.getX()-(radius/2); //logic to plot the circle in exact touch place
y=(int)event.getY()-(radius/2);
//System.out.println("X,Y:"+"x"+","+y);
randColor();
invalidate();
if (event.getAction() == MotionEvent.ACTION_UP) {
paint.setARGB(12, r, g, b);
}
return true;
}
public void randColor()
{
//r=(int)(Math.random()*255);
//g=(int)(Math.random()*255);
//b=(int)(Math.random()*255);
r=1;
g=2;
b=3;
//Toast.makeText(c, "r,g,b="+r+","+g+","+b,Toast.LENGTH_SHORT).show();
}
public void dissColor(){
r=255;
g=255;
b=255;
}
}
Related
I am pretty new to Android so I apologize ahead of time if I am missing something, but my problem is that I am trying to draw a circle at a certain location everytime I click on the screen.
I have tried logging and it does return an int where it matches my if statement but nothing gets drawn.
public boolean onTouchEvent(MotionEvent event) {
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
drawCirc = true;
xTouch = event.getX();
Log.d("keyboard", "xpos" + xTouch);
yTouch = event.getY();
break;
case MotionEvent.ACTION_UP:
drawCirc = false;
}
return true;
}
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = new Paint();
paint.setColor(Color.RED);
if(drawCirc) {
if (xTouch < 150 && xTouch>0) {
paint.setColor(Color.RED);
canvas.drawCircle(150, 500, 100, paint);
isPlayer1 = false;
invalidate();
}
}
}
#Javanator is right, you should do invalidate in touch listener.
Meanwhile, you can try out the code below, which adds animation when circle being drawn.
Paint paint = new Paint();
{
paint.setColor(Color.RED);
}
// The radius of the circle you want to draw
// 0 by default
private int radius = 0;
// The animator to animate circle drawing
private ObjectAnimator radiusAnimator;
public void setRadius(int newRadius) {
this.radius = newRadius;
this.invalidate();
}
private void showCircle(boolean show) {
ObjectAnimator animator = this.getRadiusAnimator();
if (show) {
animator.start();
} else {
animator.reverse();
}
}
private ObjectAnimator getRadiusAnimator() {
if (this.radiusAnimator == null) {
this.radiusAnimator = ObjectAnimator.ofInt(this, "radius", 0, 100);
}
return this.radiusAnimator;
}
public boolean onTouchEvent(MotionEvent event) {
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
// drawCirc = true;
xTouch = event.getX();
Log.d("keyboard", "xpos" + xTouch);
yTouch = event.getY();
showCircle(true);
break;
case MotionEvent.ACTION_UP:
// drawCirc = false;
showCircle(false);
}
return true;
}
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (xTouch < 150 && xTouch > 0) {
canvas.drawCircle(xTouch, yTouch, radius, paint);
}
/*
if(drawCirc) {
if (xTouch < 150 && xTouch>0) {
paint.setColor(Color.RED);
canvas.drawCircle(150, 500, 100, paint);
isPlayer1 = false;
invalidate();
*/
}
public class CustomView extends View {
boolean drawCirc;
float xTouch;
boolean isPlayer1;
float yTouch;
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
drawCirc=true;
xTouch = event.getX();
yTouch = event.getY();
invalidate();
}
return false;
}
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = new Paint();
paint.setColor(Color.RED);
if (drawCirc) {
paint.setColor(Color.RED);
canvas.drawCircle(xTouch, yTouch, 100, paint);
isPlayer1 = false;
invalidate();
}
}}
I have solved your functionality and Implemented sample code. I have checked it and it's working and you have not put a code in onTouch Listener that's why it's not worked but now I have solved. if you want area limit then put yourif (xTouch < 150 && xTouch>0)
I'm developing paint app the problem is when i choose color and paint and then pick different color the whole paint color changes to the new color can any one tell why this is happening and how to solve this ? and how to add eraser to this?
imageview DrawView here :
public class DrawView extends ImageView {
private ArrayList<Point> mTouches;
int paintColor;
public int setcolor(int a){
paintColor=a;
return paintColor;}
// Java constructor
public DrawView(Context context) {
super(context);
init();}
// XML constructor
public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
init();}
private void init() {
mTouches = new ArrayList<Point>();}
#Override
public boolean onTouchEvent(MotionEvent event) {
// Capture a reference to each touch for drawing
float touchX = event.getX();
float touchY = event.getY();
mTouches.add(new Point(Math.round(touchX), Math.round(touchY)));
return super.onTouchEvent(event);}
#Override
protected void onDraw(Canvas c) {
// Let the image be drawn first
super.onDraw(c);
// Draw your custom points here
Paint paint = new Paint();
paint.setColor(paintColor);
paint.setAntiAlias(true);
paint.setStrokeWidth(5);
paint.setStyle(Paint.Style.FILL);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeCap(Paint.Cap.ROUND);
for (Point p : mTouches) {
c.drawCircle( p.x, p.y,15,paint);}} }
in my main:
im.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
DrawView mcustomImagview = (DrawView) v;
mcustomImagview.setcolor(color);
mcustomImagview.invalidate();
if (v.onTouchEvent(event)) {
// Do something with event.getX(), event.getY() }
return true;}})
Every time onDraw is called, the entire canvas is redraw. As you store only one paintColor in your custom class, only the last selected one is used.
You need to store the color together with the associated Point. Then when you loop throw your mTouches array, you change the color for the color of the current Point.
Btw the Paint object can be updated, so you don't need to create it every time as it's a bad practice to create new objects in onDraw.
EDIT
public class DrawView extends android.support.v7.widget.AppCompatImageView {
private ArrayList<ColouredPoint> mTouches;
// Current used colour
private int mCurrColour;
private Paint mPaint;
public void setColor(int colour) {
mCurrColour = colour;
}
public DrawView(Context context) {
super(context);
init();
}
// XML constructor
public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
mTouches = new ArrayList<>();
mPaint = new Paint();
mPaint.setColor(mCurrColour);
mPaint.setAntiAlias(true);
mPaint.setStrokeWidth(5);
mPaint.setStyle(Paint.Style.FILL);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
// Capture a reference to each touch for drawing
float touchX = event.getX();
float touchY = event.getY();
mTouches.add(new ColouredPoint(Math.round(touchX), Math.round(touchY), mCurrColour));
return super.onTouchEvent(event);
}
#Override
protected void onDraw(Canvas c) {
// Let the image be drawn first
super.onDraw(c);
// Draw your custom points here
for (ColouredPoint p : mTouches) {
mPaint.setColor(p.colour);
c.drawCircle(p.x, p.y, 15, mPaint);
}
}
/**
* Class to store the coordinate and the colour of the point.
*/
private class ColouredPoint {
int x;
int y;
int colour;
public ColouredPoint(int x, int y, int colour) {
this.x = x;
this.y = y;
this.colour = colour;
}
}
}
I'm making an alphabet draw app where users (normally kids) will be able to fill color in the alphabet images in the app...
I've made the app which enabled me to draw anything on the canvas using the code given below...
Main Activity:
public class MainActivity extends Activity {
SimpleDrawingView view;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
view = new SimpleDrawingView (this);
setContentView(view);
view.setBackgroundResource(R.drawable.a1);
}
}
SimpleDrawingView class which actually draws on the view:
public class SimpleDrawingView extends View
{
private final int paintColor = Color.BLACK;
// defines paint and canvas
private Paint drawPaint;
// stores next circle
private Path path = new Path();
public SimpleDrawingView(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
setupPaint();
}
private void setupPaint() {
// Setup paint with color and stroke styles
drawPaint = new Paint();
drawPaint.setColor(paintColor);
drawPaint.setAntiAlias(true);
drawPaint.setStrokeWidth(15);
drawPaint.setStyle(Paint.Style.STROKE);
drawPaint.setStrokeJoin(Paint.Join.ROUND);
drawPaint.setStrokeCap(Paint.Cap.ROUND);
}
#Override protected void onDraw(Canvas canvas) {
canvas.drawPath(path, drawPaint);
}
#Override public boolean onTouchEvent(MotionEvent event) {
float pointX = event.getX();
float pointY = event.getY();
// Checks for the event that occurs
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
path.moveTo(pointX, pointY);
return true;
case MotionEvent.ACTION_MOVE:
path.lineTo(pointX, pointY);
break;
default: return false; }
// Force a view to draw again
postInvalidate();
return true;
}
}
It let me fill in the alphabet but it draws on the whole screen/view. I want to let the user fill/draw on the alphabet only and not on the entire screen.
Can someone tell me what to do or atleast some guidelines to start it ?
I want to erase my bitmap but I don't want to erase background image. When I try to erase is white and it draw very hard in frames.
This is from CanvasView
erasePaint.setColor(Color.WHITE);
//erasePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
erasePaint.setAntiAlias(true);
erasePaint.setStyle(Paint.Style.STROKE);
erasePaint.setStrokeJoin(Paint.Join.ROUND);
erasePaint.setStrokeWidth(12);
//....
protected void onDraw(Canvas canvas) {
paint.setPathEffect(null);
if(bitmap!=null){
for(MyEraser e:eraserList){
canvas.drawPath(e.p,erasePaint);
invalidate();
}
final OnTouchListener eraseListener = new OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
// erasePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
//FirstActivity.ll.setVisibility(LinearLayout.GONE);
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
myEraser = new MyEraser();
lastTouchX = event.getX();
lastTouchY = event.getY();
myEraser.mouseDown(event.getX(), event.getY());
return true;
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
resetDirtyRect(event.getX(),event.getY());
int historySize = event.getHistorySize();
for(int i=0;i<historySize;i++){
float historicalX = event.getHistoricalX(i);
float historicalY = event.getHistoricalY(i);
expandDirtyRect(historicalX, historicalY);
myEraser.mouseUp(historicalX, historicalY);
}
myEraser.mouseUp(event.getX(), event.getY());
eraserList.add(myEraser);
break;
default:
Log.d("mock it up", "Unknown touch event " + event.toString());
return false;
}
invalidate(
(int) (dirtyRect.left - HALF_STROKE_WIDTH),
(int) (dirtyRect.top - HALF_STROKE_WIDTH),
(int) (dirtyRect.right + HALF_STROKE_WIDTH),
(int) (dirtyRect.bottom + HALF_STROKE_WIDTH));
lastTouchX = event.getX();
lastTouchY = event.getY();
return true;
}
};
}
}
This is MyEraser
public class MyEraser {
Paint paint = new Paint();
Path p = new Path();
public MyEraser(){
paint.setColor(Color.WHITE);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
paint.setStyle(Paint.Style.STROKE);
paint.setAntiAlias(true);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeWidth(5);
}
public void mouseDown(float x, float y) {
//path.addCircle(x,y,5,Path.Direction.CW);
p.moveTo( x, y );
// path.lineTo(x, y);
}
public void mouseMove(Path path, float x, float y) {
// path.addCircle(x,y,5,Path.Direction.CW);
}
public void mouseUp(float x, float y){
//path.addCircle(x,y,5,Path.Direction.CW);
p.lineTo(x, y);
}
public void draw(Canvas c,Path path){
//paint.setColor(Color.WHITE);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
paint.setStyle(Paint.Style.STROKE);
paint.setAntiAlias(true);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeWidth(7);
c.drawPath(p, paint);
}
}
EDIT: Started over for better explanation :)
I am not familiar with Android, in fact I have never used it. Use this code as an example of how to organize your code, rather than a functional code.
class MyView extends View {
private Eraser myEraser;
private Bitmap myBackgroundImage;
private Canvas myForegroundCanvas;
public MyView(Context context, Attributes, attrs) {
myEraser = new Eraser()
myBackgroundImage = BitmapFactory.decodeResource(getResources(), R.drawable.your_background_name);
Bitmap image = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888); // the width and height of the view
myForegroundCanvas = new Canvas(image);
}
public boolean onTouchEvent(MotionEvent event) {
// update your eraser path
return true;
}
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(myBackgroundImage, 0, 0, null);
//for (Eraser item : eraserList) {
// if you have multiple eraser, add them to a list
myEraser.draw(myForegroundCanvas);
//}
canvas.drawCanvas(myForegroundCanvas, 0, 0, null);
}
}
The main idea is to keep the separation between your background and foreground images. That way, you could easily change the background and it would be updated. You could also have a reset on the foreground to erase everything, etc.
I hope this helps you.
I edited MyLine and CanvasView but now I draw normal line and dashed line but after that I click on normal line and it draw dashed line. Down you have mt edited code. After I created private paint in MyLine, line.paint from onDraw was transformed in getPaint
Here you have MyLine.java
public class MyLine { // line
public float x,y;
public float xStart,yStart,xEnd,yEnd;
private boolean drawDashed;
private Paint paint = new Paint();
public MyLine(boolean drawDashed)
{
if(drawDashed){
getPaint().setColor(Color.BLUE);
getPaint().setStyle(Paint.Style.STROKE);
getPaint().setPathEffect(new DashPathEffect(new float[]{20,30}, 0));
getPaint().setAntiAlias(true);
getPaint().setStrokeJoin(Paint.Join.ROUND);
getPaint().setStrokeWidth(5f);
} else{
getPaint().setColor(Color.RED);
getPaint().setStyle(Paint.Style.STROKE);
getPaint().setPathEffect(null);
getPaint().setAntiAlias(true);
getPaint().setStrokeJoin(Paint.Join.ROUND);
getPaint().setStrokeWidth(5f);
}
}
public void mouseDown(Path path,float xDown,float yDown){
//path.moveTo(xDown, yDown);
// path.lineTo(xDown, yDown);
xStart = xDown;
yStart = yDown;
}
public void mouseUp(Path path,float xUp,float yUp){
//path.lineTo(xUp, yUp);
xEnd = xUp;
yEnd = yUp;
}
public void draw(Canvas c){
getPaint().setColor(Color.GREEN);
//paint.setStyle(Paint.Style.STROKE);
getPaint().setPathEffect(new DashPathEffect(new float[]{10,20}, 0));
getPaint().setAntiAlias(true);
getPaint().setStrokeJoin(Paint.Join.ROUND);
getPaint().setStrokeWidth(5f);
c.drawLine(xStart,yStart,xEnd,yEnd,getPaint());
}
public Paint getPaint() {
return paint;
}
public void setPaint(Paint paint) {
this.paint = paint;
}
Here is from CanvasView.java
protected void onDraw(Canvas canvas) {
paint.setPathEffect(null);
if(bitmap!=null){
canvas.drawBitmap(bitmap, 0, 0, paint);
for(MyCircle circle:circleList){// draw circles
myCanvas.drawCircle(getCircleMidPointX(circle.firstX, circle.lastX),getCircleMidPointY(circle.firstY, circle.lastY),circle.radius,myPaint);
}
}
for (Path p : paths){
canvas.drawPath(p, paint);
}
canvas.drawPath(path, paint);
for(MyLine line:lineList){ //draw lines
canvas.drawLine(line.xStart, line.yStart, line.xEnd, line.yEnd, line.getPaint());
}
final OnTouchListener drawLineListener = new OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
FirstActivity.ll.setVisibility(LinearLayout.GONE);
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
myLine = new MyLine(dashedLine);
myLine.xStart = event.getX();
myLine.yStart = event.getY();
return true;
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
myLine.xEnd = event.getX();
myLine.yEnd = event.getY();
invalidate();
lineList.add(myLine);
break;
default:
Log.d("mock it up", "Unknown touch event " + event.toString());
return false;
}
return true;
}
};
final OnTouchListener drawDashedLineListener = new OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
FirstActivity.ll.setVisibility(LinearLayout.GONE);
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
return true;
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
break;
default:
Log.d("mock it up", "Unknown touch event " + event.toString());
return false;
}
return true;
}
};
b in onDraw()
if(dashedLine)
line.paint.setPathEffect(dashEffect);
else
line.paint.setPathEffect(null);
You are resetting the effect for all lines, so that is what is being drawn: all dashed or all normal
What you probaly want to do is give each MyLine its own property:
boolean drawDashed =true/false;
And let it draw itself accordingly (picking the right paint with the right dasheffect)
public class MyLine { // line
public float x,y;
public float xStart,yStart,xEnd,yEnd;
private boolean drawDashed;
private Paint paint = new Paint();
public MyLine(boolean drawDashed)
{
if(drawDashed){
...
paint.setPathEffect(new DashPathEffect(new float[]{10,20}, 0));
....
} else{
....
paint.setPathEffect(null);
...
}
}
public void mouseDown(Path path,float xDown,float yDown){
//path.moveTo(xDown, yDown);
// path.lineTo(xDown, yDown);
xStart = xDown;
yStart = yDown;
}
public void mouseUp(Path path,float xUp,float yUp){
//path.lineTo(xUp, yUp);
xEnd = xUp;
yEnd = yUp;
}
public void draw(Canvas c){
c.drawLine(xStart,yStart,xEnd,yEnd,paint);
}
}
So add two private properties to Myline so the line it self has the knowledge how to draw itself:
private boolean drawDashed;
private Paint paint = new Paint();
then the draw method becomes very simple:
public void draw(Canvas c){
c.drawLine(xStart,yStart,xEnd,yEnd,paint);
}