Select arbitrary shape drawn on Android Canvas
I have an app where I'm able to draw multiple shapes on a canvas and keep track of them in my own custom CompositeShape that has an internal ArrayList of shapes added to the screen. I want to be able to touch the screen on a specific shape and remove it. Because I'm keeping track of them in my class I can remove them if I get the right information about it. How would I be able to get the information of the shape that is selected?
My idea was to loop through my list of shapes until information from the shape I touched matches one in my list and then I can remove from my list. My Canvas is currently setup like this:
@Override
public boolean onTouchEvent(MotionEvent event) {
CommandFactory factory = CommandFactory.getInstance();
List<Object> optionList = makeList();
int xyList = new int[2];
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
xyList[0] = (int) event.getX();
xyList[1] = (int) event.getY();
optionList.add(xyList);
factory.doAction("AddShape", optionList);
invalidate();
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
break;
}
invalidate();
return true;
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
graphics.setCanvas(canvas);
try {
shapes.render(graphics, 0, 0);
} catch (ShapeException e) {
e.printStackTrace();
}
invalidate();
}
Let me know if I should provide more information about code I currently have. I'm assuming that the magic would happen somewhere in the code above.
Thanks.
java
android canvas asked Nov 16 '18 at 1:53
pianoman102pianoman102
5510
add a comment |
I have an app where I'm able to draw multiple shapes on a canvas and keep track of them in my own custom CompositeShape that has an internal ArrayList of shapes added to the screen. I want to be able to touch the screen on a specific shape and remove it. Because I'm keeping track of them in my class I can remove them if I get the right information about it. How would I be able to get the information of the shape that is selected?
My idea was to loop through my list of shapes until information from the shape I touched matches one in my list and then I can remove from my list. My Canvas is currently setup like this:
@Override
public boolean onTouchEvent(MotionEvent event) {
CommandFactory factory = CommandFactory.getInstance();
List<Object> optionList = makeList();
int xyList = new int[2];
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
xyList[0] = (int) event.getX();
xyList[1] = (int) event.getY();
optionList.add(xyList);
factory.doAction("AddShape", optionList);
invalidate();
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
break;
}
invalidate();
return true;
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
graphics.setCanvas(canvas);
try {
shapes.render(graphics, 0, 0);
} catch (ShapeException e) {
e.printStackTrace();
}
invalidate();
}
Let me know if I should provide more information about code I currently have. I'm assuming that the magic would happen somewhere in the code above.
Thanks.
java
android canvas asked Nov 16 '18 at 1:53
pianoman102pianoman102
5510
add a comment |
I have an app where I'm able to draw multiple shapes on a canvas and keep track of them in my own custom CompositeShape that has an internal ArrayList of shapes added to the screen. I want to be able to touch the screen on a specific shape and remove it. Because I'm keeping track of them in my class I can remove them if I get the right information about it. How would I be able to get the information of the shape that is selected?
My idea was to loop through my list of shapes until information from the shape I touched matches one in my list and then I can remove from my list. My Canvas is currently setup like this:
@Override
public boolean onTouchEvent(MotionEvent event) {
CommandFactory factory = CommandFactory.getInstance();
List<Object> optionList = makeList();
int xyList = new int[2];
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
xyList[0] = (int) event.getX();
xyList[1] = (int) event.getY();
optionList.add(xyList);
factory.doAction("AddShape", optionList);
invalidate();
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
break;
}
invalidate();
return true;
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
graphics.setCanvas(canvas);
try {
shapes.render(graphics, 0, 0);
} catch (ShapeException e) {
e.printStackTrace();
}
invalidate();
}
Let me know if I should provide more information about code I currently have. I'm assuming that the magic would happen somewhere in the code above.
Thanks.
java
android canvas asked Nov 16 '18 at 1:53
pianoman102pianoman102
5510
I have an app where I'm able to draw multiple shapes on a canvas and keep track of them in my own custom CompositeShape that has an internal ArrayList of shapes added to the screen. I want to be able to touch the screen on a specific shape and remove it. Because I'm keeping track of them in my class I can remove them if I get the right information about it. How would I be able to get the information of the shape that is selected?
My idea was to loop through my list of shapes until information from the shape I touched matches one in my list and then I can remove from my list. My Canvas is currently setup like this:
@Override
public boolean onTouchEvent(MotionEvent event) {
CommandFactory factory = CommandFactory.getInstance();
List<Object> optionList = makeList();
int xyList = new int[2];
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
xyList[0] = (int) event.getX();
xyList[1] = (int) event.getY();
optionList.add(xyList);
factory.doAction("AddShape", optionList);
invalidate();
case MotionEvent.ACTION_MOVE:
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_CANCEL:
break;
}
invalidate();
return true;
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
graphics.setCanvas(canvas);
try {
shapes.render(graphics, 0, 0);
} catch (ShapeException e) {
e.printStackTrace();
}
invalidate();
}
Let me know if I should provide more information about code I currently have. I'm assuming that the magic would happen somewhere in the code above.
Thanks.
java
android canvas java
android canvas asked Nov 16 '18 at 1:53
pianoman102pianoman102
5510
asked Nov 16 '18 at 1:53
pianoman102pianoman102
5510
asked Nov 16 '18 at 1:53
pianoman102pianoman102
5510
asked Nov 16 '18 at 1:53
pianoman102pianoman102
5510
asked Nov 16 '18 at 1:53
pianoman102pianoman102
5510
5510
add a comment |
add a comment |
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