New Android programmer here.
I'm trying to display an .png image as a bitmap on Android. The only way I have been able to display the converted image at all is with a custom class that extends View. However, my image is too large to be displayed entirely on the screen and I would like to be able to scroll with it. But when I define a ScrollView and put the Canvas with the Bitmap into it, I get a blank screen. I had no luck setting this up with the layout file, so it is all done in the Activity class.
This is where the Activity is created:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ScrollView scroll = new ScrollView(this);
scroll.addView(new CustomView(this));
setContentView(scroll);
}
And this is my CustomView class:
private class CustomView extends View{
public CustomView(Context context) {
super(context);
}
#Override
protected void onDraw(Canvas canvas){
Bitmap bitmapMap = BitmapFactory.decodeResource(getResources(),R.drawable.resourceimage);
canvas.drawBitmap(bitmapMap,0,0,null);
this.setWillNotDraw(false);
}
}
And if I replace this line of code in my Activity: setContentView(scroll)
with this line: setContentView(new CustomView(this)), I can see the image, albeit not the entire image. So, is there a way to set this up in the layout files instead? Or is there something I'm missing that I need to declare in the ScrollView class?
EDIT: I would prefer not to use ImageView, because I would like to change the image in specific locations, and using bitmap seemed to be the easiest way to accomplish that, via x and y coordinates.
Your custom view needs to override the onMeasure method and properly set the measured width and height so that the parent views (in this case the ScrollView) can know how much space to allocate for the child.
Related
I'm making a custom View thats derived from an ImageViewand I control where the image has to be within this ImageView using padding.
I have set OnClickListener on my custom ImageView that resizes it:
image.setOnClickListener(new ImageView.OnClickListener(){
#Override
public void onClick(View v) {
image.resize_image();
}
});
and this is how this function is looking like
public void resize_image(){
ViewGroup.LayoutParams params = getLayoutParams();
params.height = new_heigth;
params.width = new_width;
setLayoutParams(params);
}
After this resizing is done I don't want my displayed image to change size (only the custom ImageView is changing size so I can draw an extra stuff around this image) within my custom ImageView so inside onDraw(Canvas) member function I set the new padding
class custom_ImageView extends ImageView{
//...
#Override
protected void onDraw(Canvas canvas) {
//...
setPadding(new_left_padding, new_top_padding, new_right_padding, new_bottom_padding);
//...
}
//...
}
Result is that width and heigth are changed like I wanted but my displayed image is neither in the right position or size.
Interesting this is that if I add an extra line of invalidate(); in the end of my resize_image() and I click on my custom_ImageView twice - on the 2nd click image draws itself in right size and position like I wanted.
Can anyone tell me why this is happening?
I kind of worked around this by not using ImageView at all but just drawing image where it needs to be by using Canvas.drawBitmap(Bitmap, RectF, RectF, Paint)
This way I don't have to specify images location using setPadding within onDraw, but I can do it simply by specifying position using RectF.
I,m taking my first step into movement of bitmaps. From bits on the internet i,ve created this simple code. The bitmap moves across the screen from top left to top right it goes off the screen and back on at 0,0. What i want to do is add a button or method to manually move the image. I,m only using this single class and have noticed it does not use the main_activity xml Or does it?? If someone could show me on this 1 direction i can duplicate for the other directions. If youd like to add code so doesnt go off screen would be a bonus
public class MainActivity extends Activity {
int x=0;
int y=0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new myView(this)); }
private class myView extends View{
public myView(Context context) {
super(context); }
#Override
protected void onDraw(Canvas canvas) {
Bitmap myBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.richinch);
if (x < canvas.getWidth()){x +=10;}
else {x=0;}
canvas.drawBitmap(myBitmap, x, y, null);
invalidate();
}}}
Ive added this to the code and read a little on OnTouch listener. How would i add that to the region or Rectangle this would be very helpfull so effectively i,m using the Bitmap as a button if was button id know with onclick, Basicall im trying to make 2 Bitmap buttons to move the image Left Right for now.Eventually all directions. Please use names im using unless creating summit eg int etc
Paint green = new Paint();
green.setColor(Color.RED);
green.setStyle(Paint.Style.FILL);
////creating the shape////
Rect rect= new Rect();
rect.set(0, 0,x+50, x+50);
canvas.drawRect(rect,green);
Region region = new Region(0, 950, 100, 1030);
I am not exactly sure what you want to achieve, but if you would like to make an animation, avoid using onDraw() and just let ObjectAnimator do the "moving" for you. Here's a detailed tutorial on it.
The minimum code you need:
ObjectAnimator animation = ObjectAnimator.ofFloat(yourObject, "x", xDest);
animation.setDuration(500); // milliseconds
animation.start();
You are not using any xml
this part here:
setContentView(new myView(this)); is where you would add your xml file setContentView(R.layout.mainxml)
If you want to move around a bitmap with the touch of your finger check out these tutorials. They do exactly this and you will learn to use a SurfaceView
http://www.eis4u.com/2012/02/13/playing-with-graphics-in-android-part-i/
http://www.eis4u.com/2012/02/13/playing-with-graphics-in-android-part-ii/
http://www.eis4u.com/2012/02/13/playing-with-graphics-in-android-part-iii/
My problem is that I don't know how to change position of a canvas drawable on click of
my button that it's located in the main activity and not to surfaceview so the code to work should be on surfaceview here is what I've got
public class JumpOnClick extends Activity implements OnClickListener{
DrawingSurface ds;
FrameLayout frm;
Button btnC;
int color=0xfff00000;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ds=new DrawingSurface(this);
setContentView(R.layout.activity_jump_on_click);
frm=(FrameLayout)findViewById(R.id.frameLayout);
frm.addView(ds);
btnC=(Button)findViewById(R.id.buttonColor);
btnC.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// how to connect actions in here for my sprites on my surfaceview
// for example AnimatedSprite a = new AnimatedSprite();
// if(b == null)
//b=BitmapFactory.decodeStream(res.openRawResource(R.drawable.explosion));
// a.Initialize(b, 120, 159, 7, 20, true);
// mSprites.add(a);
}
}
if I understand correctly,
define two static float variables in your surfaceview class respectively x and y, and when you do your drawing in your surfaceview just use this variables as position parameters in your surfaceview's draw method. And then back in your activity in your onClick method of the button just change these x,y variables, as you can access them without any need to create object.
I believe that you need to add layout rules to your button to place it in the Surfaceview (Actually a button cant be added to a SurfaceView, you need to create an illusion with a Layout in your Activity and place the button to this Layout).
You can check this simple solution at this video https://www.youtube.com/watch?v=8qE9TQjQ5no&t=31s
that is placing buttons to a SurfaceView at the top and bottom using a Relativelayout. My opinion is with that technique you wont need the ontouchevent method neither the x,y position, you will need that if you create a button in the ondraw method (then wont be a button but a bitmap image)...My opinion is to stick with the first solution if the position is the problem so it can act as a button with the onclicklistener.
I am new for android. I want to add image button in onDraw. I wonder if I can do like this. I don't have compile error. But simulator says, "Unfortunately MyApp has stopped."
My second question is how can I add button at x, y location in screen?
There is no location parameters in addView.
protected class MyLayout extends LinearLayout {
ImageButton button;
public MyLayout(Context context) {
super(context);
setWillNotDraw(false);
button = new ImageButton(context);
button.setImageBitmap(buttonBitmap); // buttonBitmap is loaded in onCreate
}
public void onDraw(Canvas canvas) {
addView(button);
}
}
I would not be adding a button to a custom linearlayout in the onDraw() override function. onDraw is called periodically (for example when the element is resized). So you will be adding the same button EACH time onDraw() is called. And you will get an error if you add the same item more than once.
What exactly are you trying to do? If you want to just add a button to a linear layout, you can do so without extending a layout.
I am attempting to create a user interface dynamically. I have successfully create a view and loaded my background image. I have created two additional small view items to display on the background. My problem is that I have not been able to find any advice/instruction that tells me how to draw the small views. It seems that it should be a trivial exercise and I am guessing it is just finding the correct referencing. Hope someone out there can point me in the right direction.
Here is my Activity:
public class GhostActivity extends Activity implements OnTouchListener
{
private DrawView ghostView;
public Card mCard1, mCard2;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
// ToDo add your GUI initialization code here
super.onCreate(savedInstanceState);
// requesting to turn the title OFF
requestWindowFeature(Window.FEATURE_NO_TITLE);
// making it full screen
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
ghostView = new DrawView(this);
setContentView(ghostView);
//get the window size
Display display = ((WindowManager) getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
Context context = getApplicationContext();
//create view items with initial positions
Point startPoint;
startPoint = new Point();
startPoint.x = 5;
startPoint.y = 3;
mCard1 = new Card(context, 1, R.drawable.bol_geel, startPoint);
startPoint.x = 5;
startPoint.y = 43;
mCard2 = new Card(context, 2, R.drawable.bol_rood, startPoint);
//now display them on the ghostView *****************HOW?
// set the callbacks
ghostView.setOnTouchListener(this);
mCard1.setOnTouchListener(this);
mCard2.setOnTouchListener(this);
}
and here is the View;
public class DrawView extends View
{
Drawable bg ;
public DrawView(Context context) {
super(context);
//setFocusable(true);
Drawable bg = this.getResources().getDrawable(R.drawable.bubbleblue480x800);
setBackgroundDrawable(bg);
}
#Override protected void onDraw(Canvas canvas) {
// canvas.drawColor(0x0000000); //if you want another background color
//draw on the canvas
}
}
edit: I believe my problem is needing to pass a pointer to the ghostView canvas. what makes me think that is if I create the children within ghostView then call their .draw method they appear exactly as I would expect.
#Override protected void onDraw(Canvas canvas) {
canvas.drawColor(0x0000000); //if you want another background color
//draw the cards on the canvas
mCard1.draw(canvas);
mCard2.draw(canvas);
}
so at this point I am wondering how to get a reference pointer to the ghostView canvas.
To be honest I am finding the whole Activity - View relationship confusing.
Edit: I have taken a different approach based on detail in this tutorial
http://www.kellbot.com/2009/06/android-hello-circle/
It uses a FrameLayout and it seems I can achieve my objective.
To add view dynamically to view your class must extends from ViewGroup or LinearLayout class then you will able to call method addView.
Inside your ghost view first add a layout e.g Linear or Relative. Then only you could able to add views inside that layout you cant simply add a view to a xml file.
Or you can create a dynamic layout then only u can add view inside that layout.
RelativeLayout relative= new RelativeLayout(findViewById(R.id.your relativeLayoutID));
relative.addView(child);
child could be anything button textview and widget.