We Keep Coding

How to transfer data between an Activity and a View class?

I want to transfer 2 float values and 1 boolean value from my MainActivity class to MyCanvas class (which is a class extends View)? Is this possible?
I know this a newbie question, but everything that I found told to use Intent and Bundle, or to use only Bundle.setArguments(), but apparently, none of them work for a View class.
Thank you.
EDIT 1
This is my MainActivity
public class MainActivity extends AppCompatActivity {
private MyCanvas myCanvas;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myCanvas = (MyCanvas) findViewById(R.id.canvas);
}
public void btnCalcularOnClick(View v) {
TextView xResultado = (TextView) findViewById(R.id.xResultado);
TextView yResultado = (TextView) findViewById(R.id.yResultado);
EditText txtX = (EditText) findViewById(R.id.txtX);
EditText txtY = (EditText) findViewById(R.id.txtY);
//Comeco da Matematica
float x = Float.parseFloat(txtX.getText().toString());
float y = Float.parseFloat(txtY.getText().toString());
float xResult = 5 * x;
float yResult = 35 * y;
boolean buttonState = true;
}
}
MyCanvas class is like that
public class MyCanvas extends View {
Paint myPaint;
public MyCanvas(Context context, AttributeSet attrs) {
super(context, attrs);
myPaint = new Paint();
}
#Override
public void onDraw(Canvas myCanvas) {
super.onDraw(myCanvas);
myPaint.setColor(Color.BLACK);
myPaint.setStrokeWidth(3);
float cx, cy;
boolean buttonState2;
}
}
In this case, I want to transfer:
xResult (MainActivity) -> cx (MyCanvas)
yResult (MainActivity) -> cy (MyCanvas)
buttonState (Main Activity) -> buttonState2 (myCanvas)

You can use setters to set the desired values in your MyCanvas class.
Create methods in your MyCanvas class like this.
public class MyCanvas extends View {
private float cx, cy;
private boolean buttonState2;
...
public void setResults(float xResult, float yResult) {
cx = xResult;
cy = yResult;
}
public void setButtonState(boolean state) {
buttonState2 = state;
}
}
Then in your activity class
public class MainActivity extends AppCompatActivity {
private MyCanvas myCanvas;
...
public void btnCalcularOnClick(View v){
TextView xResultado = (TextView)findViewById(R.id.xResultado);
TextView yResultado = (TextView)findViewById(R.id.yResultado);
EditText txtX= (EditText)findViewById(R.id.txtX);
EditText txtY= (EditText)findViewById(R.id.txtY);
//Comeco da Matematica
float x = Float.parseFloat(txtX.getText().toString());
float y = Float.parseFloat(txtY.getText().toString());
float xResult = 5 * x;
float yResult = 35 * y;
boolean buttonState = true
myCanvas.setResults(xResult, yResult);
myCanvas.setButtonState(buttonState);
}
}

Create static variable and use it in your MyCanvas class.
In MainActvity:-
public static float var1 = 1.0f;
public static float var2 = 2.0f;
public static boolean var3 = true;
And in your MyCanvas class:-
private float var1InCanvas = MainActivity.var1;
private float var2InCanvas = MainActivity.var2;
private float var3inCanvas = MainActivity.var3;

How to convert a canvas drawing to an image then Drag it around screen?

I'm trying to draw on a canvas then onClick change it to bitmap image then I would like to make it draggable. I can draw on canvas successfully
but how do I convert this drawing to an image then make it draggable? I don't mind If it's possible to drag the drawing without converting to an image. Can someone please help.
public class MainActivity extends AppCompatActivity implements ColorPickerDialog.OnColorChangedListener {
protected DrawView canvasView;
private ImageButton blackCircle;
private Button pens,select;
private Paint mPaint;
Bitmap viewCapture = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mPaint = new Paint();
canvasView = (DrawView) findViewById(R.id.canvas_view);//The drawing mechanism
colorChanged(mPaint.getColor());
blackCircle = (ImageButton) findViewById(R.id.black_circle);
blackCircle.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
canvasView.setPathColor(Color.BLACK));
blackCircle.setPressed(true);
}
});
select = (Button) findViewById(R.id.ic_select);
select.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v) {
canvasView.setVisibility(View.VISIBLE);
canvasView.setPathColor(0);
//Drag the drawn image
setContentView(R.layout.activity_main);
relativeLayout = (RelativeLayout) findViewById(R.id.main);
drawingView = new DrawingView(MainActivity.this);
relativeLayout.addView(drawingView);
//Create a bitmap image of current drawing
canvasView.setDrawingCacheEnabled(true);
viewCapture = Bitmap.createBitmap(canvasView.getDrawingCache());
canvasView.setDrawingCacheEnabled(false);
}
});
}// End of Create();
private void clearCanvas(View v) {
canvasView.clear();
}
#Override
public void colorChanged(int color) {
mPaint.setColor(color);
canvasView.setPathColor(mPaint.getColor());
}
/************** OnTouch ***************/
class DrawingView extends View{
float x,y;
public DrawingView(Context context){
super(context);
viewCapture = BitmapFactory.decodeResource(context.getResources(), R.id.main);
}
public boolean onTouchEvent(MotionEvent event){
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_MOVE:
x =(int)event.getX();
y =(int)event.getY();
invalidate();
break;
case MotionEvent.ACTION_UP:
x =(int)event.getX();
y =(int)event.getY();
invalidate();
break;
}
return true;
}
#Override
public void onDraw(Canvas canvas) {
Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.CYAN);
canvas.drawBitmap(viewCapture, x, y, paint);
}
}
}//End of Class
public class DrawView extends View {
private Paint drawPaint, canvasPaint;
private Canvas drawCanvas;
private Bitmap canvasBitmap;
private SparseArray<Path> paths;
public DrawView(Context context) {
super(context);
setupDrawing();
}
public DrawView(Context context, AttributeSet attrs) {
super(context, attrs);
setupDrawing();
}
public DrawView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
setupDrawing();
}
private void setupDrawing() {
paths = new SparseArray<>();
drawPaint = new Paint();
drawPaint.setColor(Color.BLACK);
drawPaint.setAntiAlias(true);
drawPaint.setStrokeWidth(9);
drawPaint.setStyle(Paint.Style.STROKE);
drawPaint.setStrokeJoin(Paint.Join.ROUND);
drawPaint.setStrokeCap(Paint.Cap.ROUND);
canvasPaint = new Paint(Paint.DITHER_FLAG);
}
#Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
canvasBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
drawCanvas = new Canvas(canvasBitmap);
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint);
for (int i=0; i<paths.size(); i++) {
canvas.drawPath(paths.valueAt(i), drawPaint);
}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
int index = event.getActionIndex();
int id = event.getPointerId(index);
Path path;
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
case MotionEvent.ACTION_POINTER_DOWN:
path = new Path();
path.moveTo(event.getX(index), event.getY(index));
paths.put(id, path);
break;
case MotionEvent.ACTION_MOVE:
for (int i=0; i<event.getPointerCount(); i++) {
id = event.getPointerId(i);
path = paths.get(id);
if (path != null) path.lineTo(event.getX(i), event.getY(i));
}
break;
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
path = paths.get(id);
if (path != null) {
drawCanvas.drawPath(path, drawPaint);
paths.remove(id);
}
break;
default:
return false;
}
invalidate();
return true;
}
public void setPathColor(int color) {
drawPaint.setColor(color);
}
public void clear() {
canvasBitmap.eraseColor(Color.TRANSPARENT);
paths.clear();
invalidate();
System.gc();
}
}

For the next steps I assume you'd like to let the users drag the picture which they just created with the DrawView. So I'd introduce another View which can display the bitmap and set its position and dimensions exactly like those of the DrawView. (The best way to achieve this depends on the type of ViewGroup you are using)
Create a bitmap from the canvas as shown in converting a canvas into bitmap image in android
Set the bitmap as the new View's background with setBackground(Drawable), toggle the visibility of both Views as needed.
To make the new View draggable, use a View.OnTouchListener and change the position according to the MotionEvents
Another option: just drag the DrawView by using a flag to indicate whether the users can drag it or draw on it. You override onTouchEvent() already, now check the flag first and if it is set to "drag" then evaluate the delta between two MOVEs and adjust the position accordingly.

ViewPager carousel not showing properly with small images

Hi I'm new in android and recently I made a carousel with viewpager using this and it works fine with full width height images but when i resize images it doesn't work properly by that I mean it takes the entire width of the screen instead of specified width.
The actual idea is to have a carousel at the bottom of the page with small images.
So this is where I'm stuck and need some help actually I don't have much idea about this so I would appreciate some help.
Thank you
My code are below as follows
CarouselTransformer.class
public class CarouselEffectTransformer implements ViewPager.PageTransformer {
private int maxTranslateOffsetX;
private ViewPager viewPager;
public CarouselEffectTransformer(Context context) {
this.maxTranslateOffsetX = dp2px(context, 180);
}
public void transformPage(View view, float position) {
if (viewPager == null) {
viewPager = (ViewPager) view.getParent();
}
int leftInScreen = view.getLeft() - viewPager.getScrollX();
int centerXInViewPager = leftInScreen + view.getMeasuredWidth() / 2;
int offsetX = centerXInViewPager - viewPager.getMeasuredWidth() / 2;
float offsetRate = (float) offsetX * 0.38f / viewPager.getMeasuredWidth();
float scaleFactor = 1 - Math.abs(offsetRate);
if (scaleFactor > 0) {
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
view.setTranslationX(-maxTranslateOffsetX * offsetRate);
//ViewCompat.setElevation(view, 0.0f);
}
ViewCompat.setElevation(view, scaleFactor);
}
/**
* Dp to pixel conversion
*/
private int dp2px(Context context, float dipValue) {
float m = context.getResources().getDisplayMetrics().density;
return (int) (dipValue * m + 0.5f);
}
}
PagerAdapter
public class MyPagerAdapter extends PagerAdapter{
Context context;
int adapterType;
ArrayList<NearbyDataProvider> arrayList = new ArrayList<>();
public MyPagerAdapter(Context context,ArrayList<NearbyDataProvider> arrayList, int adapterType) {
this.context = context;
this.arrayList = arrayList;
this.adapterType=adapterType;
}
#NonNull
#Override
public Object instantiateItem(#NonNull ViewGroup container, int position) {
View view = LayoutInflater.from(context).inflate(R.layout.item_cover, null);
try {
NearbyDataProvider nearbyDataProvider = arrayList.get(position);
LinearLayout linMain = (LinearLayout) view.findViewById(R.id.linMain);
RoundedImageView imageCover = (RoundedImageView) view.findViewById(R.id.imageCover);
CustomTextViewMedium customTextViewMedium = (CustomTextViewMedium)view.findViewById(R.id.imageTitle);
CustomTextViewMedium customTextViewMedium1 =(CustomTextViewMedium)view.findViewById(R.id.imageContent);
linMain.setTag(position);
switch (adapterType)
{
case NearbyFragment.ADAPTER_TYPE_TOP:
break;
case NearbyFragment.ADAPTER_TYPE_BOTTOM:
linMain.setBackgroundResource(0);
break;
}
GlideApp.with(context)
.load(arrayList.get(position).getImage())
.into(imageCover);
customTextViewMedium.setText(nearbyDataProvider.getPlace());
container.addView(view);
} catch (Exception e) {
e.printStackTrace();
}
return view;
}
#Override
public int getCount() {
return arrayList.size();
}
#Override
public boolean isViewFromObject(#NonNull View view, #NonNull Object object) {
return (view == object);
}
#Override
public void destroyItem(#NonNull ViewGroup container, int position, #NonNull Object object) {
container.removeView((View) object);
}
}

android how do I update the view to include a custom graphic?

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);

Trying to fix my code but I keep failing :(

I've got this code that makes the image turn into a circle using a ListView. But as seen in the image, it dies when it goes to the end of the photo (the last few pixels are carried on when there not supposed to).
I don't want the photo to take up the whole page, just the size of the photo. Here's the code and XML:
Stream item 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="wrap_content" >
</RelativeLayout>
activity stream xml:
<ListView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/main_list"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:divider="#null"
android:dividerHeight="0px"
android:drawSelectorOnTop="true"
tools:context=".StreamActivity" />
main code:
public class StreamActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_stream);
StreamAdapter adapter = new StreamAdapter(this);
((ListView) findViewById(R.id.main_list)).setAdapter(adapter);
adapter.add(new StreamItem(this, R.drawable.testimage1, null, null));
adapter.add(new StreamItem(this, R.drawable.testimage1, null, null));
adapter.add(new StreamItem(this, R.drawable.testimage1, null, null));
adapter.add(new StreamItem(this, R.drawable.testimage1, null, null));
}
class StreamItem {
final Bitmap mBitmap;
StreamItem(Context c, int resid, String line1, String line2) {
mBitmap = BitmapFactory.decodeResource(c.getResources(), resid);
}
}
class StreamDrawable extends Drawable {
private static final boolean USE_VIGNETTE = true;
private final float mCornerRadius;
private final RectF mRect = new RectF();
private final BitmapShader mBitmapShader;
private final Paint mPaint;
private final int mMargin;
StreamDrawable(Bitmap bitmap, float cornerRadius, int margin) {
mCornerRadius = cornerRadius;
mBitmapShader = new BitmapShader(bitmap,
Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setShader(mBitmapShader);
mMargin = margin;
}
#Override
protected void onBoundsChange(Rect bounds) {
super.onBoundsChange(bounds);
mRect.set(mMargin, mMargin, bounds.width() - mMargin, bounds.height() - mMargin);
if (USE_VIGNETTE) {
RadialGradient vignette = new RadialGradient(
mRect.centerX(), mRect.centerY() * 1.0f / 0.7f, mRect.centerX() * 1.3f,
new int[] { 0, 0, 0x7f000000 }, new float[] { 0.0f, 0.7f, 1.0f },
Shader.TileMode.CLAMP);
Matrix oval = new Matrix();
oval.setScale(1.0f, 0.7f);
vignette.setLocalMatrix(oval);
mPaint.setShader(
new ComposeShader(mBitmapShader, vignette, PorterDuff.Mode.SRC_OVER));
}
}
#Override
public void draw(Canvas canvas) {
canvas.drawRoundRect(mRect, mCornerRadius, mCornerRadius, mPaint);
}
#Override
public int getOpacity() {
return PixelFormat.TRANSLUCENT;
}
#Override
public void setAlpha(int alpha) {
mPaint.setAlpha(alpha);
}
#Override
public void setColorFilter(ColorFilter cf) {
mPaint.setColorFilter(cf);
}
}
class StreamAdapter extends ArrayAdapter<StreamItem> {
private static final int CORNER_RADIUS =100; // dips
private static final int MARGIN = 1; // dips
private final int mCornerRadius;
private final int mMargin;
private final LayoutInflater mInflater;
public StreamAdapter(Context context) {
super(context, 0);
final float density = context.getResources().getDisplayMetrics().density;
mCornerRadius = (int) (CORNER_RADIUS * density + 0.5f);
mMargin = (int) (MARGIN * density + 0.5f);
mInflater = LayoutInflater.from(getContext());
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewGroup view = null;
if (convertView == null) {
view = (ViewGroup) mInflater.inflate(R.layout.stream_item, parent, false);
} else {
view = (ViewGroup) convertView;
}
StreamItem item = getItem(position);
StreamDrawable d = new StreamDrawable(item.mBitmap, mCornerRadius, mMargin);
view.setBackgroundDrawable(d);
int w = item.mBitmap.getWidth();
int h = item.mBitmap.getHeight();
float ratio = w / (float) h;
LayoutParams lp = view.getLayoutParams();
lp.width = getContext().getResources().getDisplayMetrics().widthPixels;
lp.height = (int) (lp.width / ratio);
return view;
}
}
}