Can you please tell me how does android determine when View should enable the drawing cache? I try calling in my class (which inherits form LinearLayout) Bitmap drawingCache = getDrawingCache(); I get a null in my drawingCache.
View 5 Replies
I'm working with Android 2.1 and have the following problem:
Using the method View.getDrawingCache() always returns null. getDrawingCache() should return a Bitmap, which is the presentation of View's content.
Example code:
public void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final View view = findViewById(R.id.ImageView01);
view.setDrawingCacheEnabled(true);
view.buildDrawingCache();
final Bitmap bmp = view.getDrawingCache();
System.out.println(bmp);
}
I've already tried different ways to configure the View object for generating the drawing cache (e.g. View.setWillNotDraw(boolean) and View.setWillNotCacheDrawing(boolean)), but nothing works. What is the right way, or what I'm doing wrong? In real code I want to apply getDrawingCache() on a ViewGroup like RelativeLayout. Is the behaviour the same when using a ViewGroup?
From the JavaDoc, it said it returns 'a bitmap representing this view or null if cache is disabled'. My question is what if the View is longer than the phone screen (you need to scroll vertically), what does the bitmap return? * only the visible portion of the view * everything the view has (both visible + invisible part)
View 4 Replies View RelatedWould anyone please try to explain to me why
public void addView(View child) {
child.setDrawingCacheEnabled(true);
child.setWillNotCacheDrawing(false);
child.setWillNotDraw(false);
child.buildDrawingCache();
if(child.getDrawingCache() == null) { //TODO Make this work!
Log.w("View", "View child's drawing cache is null");
}
setImageBitmap(child.getDrawingCache()); //TODO MAKE THIS WORK!!!
}
ALWAYS logs that the drawing cache is null, and sets the bitmap to null? Do I have to actually draw the view before the cache is set?
I'm having a small problem with drawing a View offscreen to a Bitmap. The View is created using LayoutInflater.inflate(int resource, ViewGroup root) with null passed to the root parameter. The View has a fixed size (200x180 pixels). I can create a Bitmap for this View either by using the method View.getDrawingCache() or by calling View.draw(Canvas canvas) using a Canvas that in turn has a backing Bitmap. This works fine if the View doesn't change after the inflate. However, if I have a TextView inside my View that I will update, the size of the TextView is never updated regardless of what method I call on the View (requestLayout(), forceLayout() invalidate() etc.). If I display the View on screen directly, everything works fine (sizes are updated as needed, etc.). What is the correct way of drawing Views off screen and being able to update their layout when needed?
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View 2 Replies View RelatedI am facing some problem Like:
Scenario:Three buttons enabled by on click event.
-I am using sliding drawer... on which no of buttons are there. -When sliding drawer is opened...its overlapping the preveously defined three buttons.
My problem is... when i am clicking on sliding drawer ... the below button is activated and accordingly it goes to next activity...
Means ... i expect if one view is on top of another view... the lower view should not work.
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View 1 Replies View RelatedI'm implementing an image cache system for caching downloaded image.
My strategy is based upon two-level cache:
Memory-level and disk-level.
My class is very similar to the class used in the droidfu project
My downloaded images are put into an hashmap and the Bitmap objet is wrapped inside a SoftRererence object.
Also every image is saved permanently to the disk.
If a requested image is not found into the Hashmap<String,SoftReference<Bitmap>> it will be searched on the disk, readed, and then pushed back into the hashmap. Otherwise the image will be downloaded from the network.
Since I store the images into the phisical device momery, I have added a check for preserve the device space and stay under a 1M of occupied space:
CODE:.................
This method is called sometime afte a disk writing:
CODE:..............
What I'd like to add is the same check on the HashMap size to prevent it will grow too much. Something like this:
CODE:.....................
My question is:
What could be a right MAX_MEMORY_SIZE value? Also, Is it a good approach? A good answer also could be: "Don't do it! SoftReference is already enough"
What is your best drawing app?
I've tried Draw!, Draw(er), and MagicMarker, but I dunno, they each have their pros and cons and can't find one that suits me well. I'm not looking for Photoshop on my phone, but something better than a colored line. So what is your best drawing app?
I am trying to set up a ViewFlipper that changes a SlidingDrawers content each time a button is pressed. So far every view I set up worked fine, but now I am trying to create a ListView (including single_choice_mode) within a child view of the ViewFlipper, but my attempt only let to a NullPointerException. As I only discovered ViewFlipper today, I am not yet familiar with it and may not have understood it completely. if someone could give me a hand and help me find out what I have done wrong, that would be great. Here is what I have done:
The code for the onClick event of the ImageButtons:
public void onClick(View v){
if (v == btnExposure){
mFlipper.setDisplayedChild(0); }
else if (v == btnProperties){
mFlipper.setDisplayedChild(1);}
else if (v == btnSpecialEffects){
mFlipper.setDisplayedChild(2);.............
This is more of a question about animating than a specific problem coding. i need to fill in the broad strokes left by the research i've been doing.
What i'm trying to do:
The activity should load with only the a togglebutton visible. when the button is touched, a png will be animated to a certain position relative to the togglebutton. also, another button will slide in from off screen and slide off if/when the togglebutton is pressed again.
What i can't figure out:
I can draw an image, but only via xml. creating an imageview and setting the background programmatically does nothing.
When i draw from xml, i can't move the image when the togglebutton is pressed like i want to. when i call getPositionOnScreen() i get a null pointer, even though the complier can see i'm referring to the imageview described in both xml and in code.
I'm calling getPositionOnScreen because via xml, i have the image positioned behind the togglebutton so that it's not visible until the button has been pressed and the image starts moving. the idea is that with different screen sizes i won't know exactly where the view is until runtime. getPostionOnScreen allows me to get the coordinates of the imageview so i know where it has been positioned. when i have a start position, can tell it to "move up" on the screen from behind the togglebutton by simply adding to x or y until it's where i want.
This is the code to draw the image (inserted in the onCreate method).
CODE:.......
This is the code i'm using to animate. when the button is clicked, it calls this method on the view from the listener.
CODE:...............
I'm well aware that this is horribly wrong and won't work. what i need to understand is why.
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I've got it so that the patterns draw - I took the LunarLander sample as a starting point, and an drawing on a SurfaceView. But my problem is with timing the 'animations'. I'm not doing traditional animation, where I build a whole frame and then draw it, but the surface seems to want to draw itself completely on each iteration of my loop, so my inserted sleep's don't insert delay in the right places.
So my questions:
1. Is there a more direct way to write to the screen than via a SurfaceView? If I did that, would the various steps of my 'animation' occur as I drew them, producing the desired effect. 2. If such a drawing method exists, would I be wasting my time learning how to use it? 3. What's the 'standard' way to do this kind of animation?
Is there any api for drawing financial chart in android.
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1) create a canvas A
2) create bitmap.
3) set bitmap on canvas A
4) draw the new page content on canvas A
5) the current showing page has been saved in bitmap before since we do from step 1) to setp 4),
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7) when step 6) is done, it means the new page has been shown on screen, and the bitmap has been saved to use in next page turning.
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When I try extending the View class to a subclass that will underline portions of the text drawn by ListView, the code compiles okay but results in a runtime exception apparently due to an improper class cast. Does anyone see what I've done wrong or have suggestions about getting access to the Canvas of ListView items so portions of text can be underlined?
Here is the code, which is the Efficient Adapter View/List example from ApiDemos with an added UnderlinedView class.
CODE:........