I am creating a POC on how to resize an imageView in android. I want to put 4 squares in the corner of the ImageView so I can drag the squares to resize. What should I use to get this result?
Get the coordinate of the corners
Draw rectangles at those coordinates with method like Canvas.drawRect(float left, float top, float right, float bottom, Paint paint)
Get the coordinates of the touch point from onTouch()
Resize the imageview with the new size
Get Coordinates of Touch Point
The class (suppose it is an Activity) should implements OnTouchListener, and register the listener to itself
public class MyActivity extends Activity implements OnTouchListener {
...
setOnTouchListener(MyActivity.this);
...
#Override
public boolean onTouch(View v, MotionEvent event) {
int action = event.getActionMasked();
switch(action) {
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_MOVE:
break;
case MotionEvent.ACTION_UP:
// Get the coordinates
int x = (int)event.getRawX();
int y = (int)event.getRawY();
// Resize the imageView
resize();
break;
case MotionEvent.ACTION_CANCEL:
break;
}
return true;
}
}
Resize the ImageView
You can use ImageView.setMaxHeight(), ImageView.setMaxWidth() to resize the imageview
By the way, does the imageView you want to resize is in fact an image? In that case, using drawable might be a better idea
Maybe an overlay is what you need.
Create a 9-patch drawable with the squares and corners and put that layer on top of your imageview.
Related
Move rectangle on finger touch event and also Resize rectangle by moving it left ,right, top or bottom line finger touch and rotate it when I touch or move on bottom right corner of the rectangle(show in figure) and redraw it (canvas) android please help if anyone can.
If you have all in a child class from View you could override
#Override
public boolean onTouchEvent(MotionEvent event) {
final Point point = new Point((int) event.getX(), (int) event.getY());
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
press(point);
break;
case MotionEvent.ACTION_MOVE:
drag(point);
break;
case MotionEvent.ACTION_UP:
release(point);
break;
}
return true;
}
In the method press(Point point) you need to identify with point to point or point to line distance which feature is the most near to be selected. And the method drag(Point point) helps you to drag the rect.
Drawing
Drawing should take place in the onDraw(Canvas canvas) method but the instantiation should be outside this method. So you create the Rect in your constructor or so
Rect rect = new rect(10, 10, 100, 100)
Resize
When you try to resize you don't need to create a new Rect you'll just use
rect.set(x, y, dx, dy)
Rotate
When you want to rotate you need to rotate the Canvas then draw and afterwards rotate back to draw something else.
canvas.save();
canvas.rotate(45);
canvas.drawRect(rect, paint);
canvas.restore();
I have created my own component which extends RelativeLayout, inside it I have a field of View type which is being positioned with margins:
Blue quad represents my parent view, and a red circle is a child.
Now I want to allow user to move this red circle while moving a finger on a screen.
This is my onTouchEvent() method:
#Override
public boolean onTouchEvent(MotionEvent event) {
int eventAction = event.getAction();
switch (eventAction) {
case MotionEvent.ACTION_DOWN:
// finger touches the screen
break;
case MotionEvent.ACTION_MOVE:
marginX = (int)event.getX();
marginY = (int)event.getY();
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams)pointer.getLayoutParams(); // pointer is this red circle
lp.setMargins(marginX, marginY, 0, 0);
break;
case MotionEvent.ACTION_UP:
// finger leaves the screen
break;
}
return true;
}
But I quickly found out that it doesn't refresh it's position while user is moving his finger on a screen, but instead it does it only when user releases his finger from the screen. So basically, when I move my finger, circle stays in a same position, but when I stop moving, circle is drawn in new position. I tried using invalidate() method on both, parent and child views, but it didn't help. I assume that it may have something to do with UI thread, but I don't have access to runOnUiThread()' method as it's not anActivity`.
EDIT:
I passed an activity to my class, so that I can use runOnUiThread(). My case: ACTION_MOVE now looks like this:
case MotionEvent.ACTION_MOVE:
marginX = (int)event.getX();
marginY = (int)event.getY();
activity.runOnUiThread(new Runnable() {
public void run() {
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams)pointer.getLayoutParams();
lp.setMargins(marginX, marginY, 0, 0);
pointer.invalidate();
}
});
break;
If it's simple pointer you can draw it on Canvas as Drawable:
#Override
protected void onDraw(Canvas canvas) {
pointer.setBounds(marginX, marginY, marginX + pointerWidth, marginY + pointerHeight);
pointer.draw(canvas);
super.onDraw(canvas);
}
And then call invalidate() on pointer in onTouchEvent() method.
I think you need drag and drop function
Refer http://www.vogella.com/articles/AndroidDragAndDrop/article.html
I want to draw a circle when ever user touches any place on the screen.I know to draw the circle using canvas,but how the drawn circles should be positioned to screen?
Does the surface view help for me?
Thanks in advance.
You can use the Activity.onTouchEvent event to determine where the user touched the screen. Then you can draw your circle on the canvas at that position.
Here's an example that handles a simple touch event.
#Override
public boolean onTouchEvent(MotionEvent ev) {
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
final float x = ev.getX();
final float y = ev.getY();
// draw circle at x,y
}
}
Now I have an ImageView and its a circle which is at the slightly below than center position (But this should not matter).
I have written code onTouch of ImageView for ACTION_DOWN,ACTION_UP ,now consider as user have put finger on circle and move and move.... I want to active some code when user move finger and exceed the region of CIRCLE image(As soon as user exceed the region the code should be ececuted onlly once)
Here is my code
ImageView view1 = (ImageView) findViewById(R.id.fccircledetectionarea);
view1.setOnTouchListener(new OnTouchListener()
{
#Override
public boolean onTouch(View v, MotionEvent event)
{
ImageView imageView=(ImageView) findViewById(R.id.fccircledetectionarea);
switch(event.getAction())
{
case MotionEvent.ACTION_DOWN:
final float x=imageView.getTop();
Toast.makeText(PlayScreen.this, "Top Position:"+x, Toast.LENGTH_SHORT).show();
break;
case MotionEvent.ACTION_UP:
Toast.makeText(PlayScreen.this, "Over", Toast.LENGTH_SHORT).show();
break;
case MotionEvent.ACTION_MOVE:
Toast.makeText(PlayScreen.this, "Over", Toast.LENGTH_SHORT).show();
break;
}
return true;
}
});
I cannot archive my goal through ACTION_MOVE: as it start to work if user move finger within the circle
And my second query is that How to set alpha of this imageview I have used
view1.setAlpha(0);
But is not working and I have also made this imageview invisible but than my onTouch code is not working
Within your onTouch method record a boolean to check if the user is touching within the bounds of the circle.
boolean inCircle = java.lang.Math.sqrt(x*x + y*y) <= circleRadius
Where x is taken from event.getX() - circleCenterX and y is taken from event.getY() - circleCenterY (touch position's offset from center of the circle)
I have a table-top style game board consisting of 10x10 squares. Each square is a PNG image. On top of these squares I want to place tiles which can be drag and dropped on top of the squares.
What would be my best approach concerning Views?
Is it possible to have two layers where layer one is a grid of ImageView's which represents the board. Would it then be possible to let the tile be an ImageView also which could be "stacked" on top of the ImageView's which represents the board?
Any good design ideas are welcome!
Thanks.
/ Henrik
Override onTouchEvent in your View:
#Override
public boolean onTouchEvent(MotionEvent event) {
super.onTouchEvent(event);
if (!mEnable) {
return false;
}
int action = event.getAction();
int x = (int)event.getX();
int y = (int)event.getY();
switch (action) {
case MotionEvent.ACTION_DOWN:
onTouchActionDown(x, y);
break;
case MotionEvent.ACTION_MOVE:
onTouchActionMove(x, y);
break;
case MotionEvent.ACTION_UP:
onTouchActionUp(x, y);
break;
}
return true;
}
Then in either onTouchActionUp/Down just use the co-ordinates and redraw your image resource, i.e. invalidate() your view.
Override onDraw to draw the dragged graphic:
#Override
protected void onDraw(Canvas canvas)
drawMyDragGfx();
}
I did a override on onDraw and onTouchEvent in my View. I.e. I did the drag and drop drawing all by myself.
Worked like a charm :-)