I'm working on my first game app, when user touches an image the app shows a message to the user (or does other things in other situations).
My photos are non-geometric shapes (for example animal photos) with 100% transparent backgrounds
(I used Photoshop and saved them in PNG format.)
My problem is that I need it to react (and show the message,...) only when the animal shape itself (NOT the imageview's transparent background/corners) is touched by user.
I used the solution that's offered in this question to find out if the pixel that's touched is transparent or not, but it doesn't work the way I need. Here's part of my onCreate() method in MainActivity.java:
tempIV=(ImageView)findViewById(R.id.birdIV);
final Bitmap bitmap = (BitmapDrawable)tempIV.getDrawable()).getBitmap();
tempIV.setOnTouchListener(new View.OnTouchListener(){
#Override
public boolean onTouch(View v, MotionEvent event){
int x = (int)event.getX();
int y = (int)event.getY();
int transparency = bitmap.getPixel(x,y);
if (transparency == 0)
{ //Do nothing
return false;}
else {
Toast.makeText(MainActivity.this,
"This is an animal!", Toast.LENGTH_LONG).show();
}
return true;
}
});
What should I do?
Try using this :-
if (bitmap.getPixel(x, y) == Color.TRANSPARENT)
{
return false; //don't react
}
else
{
return true; //do something like intent
}
Related
I wan't to use a image view like below, to create a virtual cross controller or d-pad (It's not possible in my case to do this with different buttons).
When the cross image is displayed on the screen, I wan't to check on wich side the user has pressed to call a function like up(), down(), left() and right().
Cross image:
imageView1.setOnTouchListener(new View.OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
int x = (int)event.getX();
int y = (int)event.getY();
if((x>170&&x<230)&&(y>0&&y<170))
{//up
Toast.makeText(MainActivity.this,"up",Toast.LENGTH_SHORT).show();
}
else if((x>170&&x<230)&&(y>230&&y<400))
{//down
Toast.makeText(MainActivity.this,"down",Toast.LENGTH_SHORT).show();
}
else if((x>0&&x<170)&&(y>170&&y<230))
{//left
Toast.makeText(MainActivity.this,"left",Toast.LENGTH_SHORT).show();
}
else if((x>230&&x<400)&&(y>170&&y<230))
{//right
Toast.makeText(MainActivity.this,"right",Toast.LENGTH_SHORT).show();
}
return false;
}
});
//take iamge view 400px*400px
I use Android studio and I have this image with a transparent background. Whenever i click on it it'll bring me to another Activity. But even when I click on the transparent part of the image it'll bring me to the other Activity.
Is it possible to make the nontransparent part clickable (or touchable) and the transparent part unclickable?
Yes this is possible but it becomes much more difficult than just adding an OnClickListener.
The trick is to use a Touch listener instead of click and on either a DOWN or UP event take the position and then either use some simple maths to work out whether it was a transparent area (if the design is a simple one) or, do some more complicated stuff to work out your pixel values at the centre.
new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
If (event.getAction() == MotionEvent.ACTION_DOWN) {
final int x = (int) event.getX();
final int y = (int) event.getY();
//now map the coords we got to the
//bitmap (because of scaling)
ImageView imageView = ((ImageView)v);
Bitmap bitmap =((BitmapDrawable)imageView.getDrawable()).getBitmap();
int pixel = bitmap.getPixel(x,y);
//now check alpha for transparency
int alpha = Color.alpha(pixel);
If (alpha != 0) {
//do whatever you would have done for your click event here
}
}
return true; //we've handled the event
}
}
I am currently developing an Android app that displays multiple images (as ImageView's) stacked on top of each other. Here is how the layers are currently configured:
Background layer: scales the entire screen, must be clickable
Foreground layer: scales the entire screen, must be clickable,
contains transparency which allows the user to see some of the
background layer
The problem I face is with the foreground layer. I am assigning the onClick() method to the imageview, but the method is being called whether they hit the portion of the image which is visible as well as the part which contains transparency. I only want the foreground ImageView onClick() method to be called when the user clicks a portion of that imageview that is not transparent.
This is what the scenario looks like:
The diagonal lines represent the transparent portion of the Foreground image. If a user touches this space, I want it to access the Background image instead of the Foreground image. Thank you for any assistance you can provide.
Here is the solution I implemented (Thanks to answer below):
//ontouchlistener - gets X and Y from event
private void setClick(View view)
{
view.setOnTouchListener(new View.OnTouchListener()
{
public boolean onTouch(View v, MotionEvent event)
{
int imageId = getImageId((int)event.getX(), (int)event.getY());
if (imageId >= 0)
performActions(imageId);
return false;
}
});
}
//get the ID of the first imageview (starting from foreground,
//working backwards) which contains a non-transparent pixel
private int getImageId(int x, int y)
{
ViewGroup parent = (ViewGroup) findViewById(R.id.relative_layout);
for (int a = parent.getChildCount()-1; a >= 0; a--)
{
if (parent.getChildAt(a) instanceof ImageView)
if (!checkPixelTransparent((ImageView)parent.getChildAt(a), x, y))
return parent.getChildAt(a).getId();
}
return -1;
}
//get bitmap from imageview, get pixel from x, y coord
//check if pixel is transparent
private boolean checkPixelTransparent(ImageView iv, int x, int y)
{
Bitmap bitmap = ((BitmapDrawable) iv.getDrawable()).getBitmap();
if (Color.alpha(bitmap.getPixel(x, y)) == 0)
return true;
else
return false;
}
This one sample makes ImageView's transparent area not clickable.
ImageView:
ImageView imgView= (ImageView) findViewById(R.id.color_blue);
imgView.setDrawingCacheEnabled(true);
imgView.setOnTouchListener(changeColorListener);
OnTouchListener:
private final OnTouchListener changeColorListener = new OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
Bitmap bmp = Bitmap.createBitmap(v.getDrawingCache());
int color = bmp.getPixel((int) event.getX(), (int) event.getY());
if (color == Color.TRANSPARENT)
return false;
else {
//code to execute
return true;
}
}
};
If your foreground image is not just a rect but a complex image and you really need that the touch is pixel-precise, you may use
http://developer.android.com/reference/android/view/View.OnTouchListener.html
foregroundImage.setOnTouchListener(new View.OnTouchListener(){...});
The MotionEvent in the callback will contain what kind of action happened (e.g. Touch up) and the exact location.
If you know the exact size of the foreground image as it is displayed, you can figure out which pixel of it was clicked, then check if that pixel's alpha is 0. Or you may need to apply some scaling if the image was scaled. This may get quite tricky since depending on the screen size and proportions the image may have been scaled/positioned differently. This also depends on the layouts your were using.
For the check of the pixel value you'd probably need to keep in memory the Bitmap object containing your foreground's image data as well.
Frankly, I doubt you'd really need all that precision unless your foreground image is really of a very irregular shape.
Bitmap.createBitmap(v.getDrawingCache() and imageView.setDrawingCacheEnabled(true) are depreciated so you can do this by the following snippet code:
imageView.setOnTouchListener { v, event ->
val bmp = convertViewToDrawable(v)
val color: Int = bmp.getPixel(event.x.toInt(), event.y.toInt())
if (color == Color.TRANSPARENT)
return#setOnTouchListener false
else {
Toast.makeText(baseContext, "image clicked", Toast.LENGTH_SHORT).show()
return#setOnTouchListener true
}
}
private fun convertViewToDrawable(view: View): Bitmap {
val b = Bitmap.createBitmap(view.measuredWidth, view.measuredHeight,
Bitmap.Config.ARGB_8888)
val c = Canvas(b)
c.translate((-view.scrollX).toFloat(), (-view.scrollY).toFloat())
view.draw(c)
return b
}
I'm drawing an rectangle surface by using canvas and i want to disable onTouchEvent() of some part of area, example if you tap(Touch) right side of the rectangle it should not perform onTouchEvent(). can any one tell me How to do this. Thanks in advance.
You have to use Hit and Trial method and generate a formula to run your app on different screen size of devices. And check where the user clicked and if he clicked in the restricted region do nothing.
Like
#Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
int x = (int)event.getX();
int y = (int)event.getY();
if (x<height-100 && y>width-100) {
// Do nothing
}
return super.onTouchEvent(event);
}else{
//Do what you want here
}
I'm drawing a number of bitmaps on a canvas, and using MotionEvents to let me drag them around.
When each item is pressed, I'd like to display a Toast, or, Toast-like mini information-panel that tracks the movement of the bitmap being dragged during an ACTION_MOVE. The "Toast" would appear on ACTION_DOWN and vanish on ACTION_UP.
The problem with using Toast is that I have to give it a duration, and, also, I can't change its position once it has been displayed. Unless I can kill the Toast for each ACTION_MOVE, and display a new one right away at the current coordinates? (Sorry, thinking aloud at this point, can't get to my dev machine to test...)
I don't know what other options there might be to achieve this, and I'd very much appreciate suggestions from the community.
Hope this helps, just whipped it up, might even compile!
private boolean mDragging = false;
private float mTouchX = 0, mTouchY = 0;
private Paint mTextPaint = new Paint();//need to set this up in onCreate!
public boolean onTouchEvent(MotionEvent event)
{
mTouchX = event.getX();
mTouchY = event.getY();
if(event.getAction() == ACTION_DOWN)
{
mDragging = true;
}
else if(event.getAction() == ACTION_UP)
{
mDragging = false;
}
return true;
}
protected void onDraw (Canvas canvas)
{
/* Put all your bitmap drawing here. */
/* Draw some info text on top of everything else. */
if(mDragging)
{
String text = mTouchX + ", " + mTouchY;
canvas.drawText(mTouchX, mTouchY + 50, text, mTextPaint);
}
}
A Toast isn't suitable in this case for reasons you already mentioned. It will be better to define a region on the Canvas and draw the message string there using drawText. Put this in the onDraw method and call invalidate whenever you need to update the text or the position of the message board.