How can I fill the screen with texture? I can get screen size and density, also a bitmap size. But what next? should I transform texture with matrix or use special paint? Anything else? Thanks.
How about
Bitmap background = Bitmap.createScaledBitmap
(YourBitmap, ScreenWidth, ScreenHeight, false);
You've got a blank canvas, there's all kinds of things you can do with it! For example, to draw a bitmap, you could add the bitmap to res/drawable and do something like
bitmap = BitmapFactory.decodeResource(caller.getResources(), r_bitmap);
canvas.drawBitmap(bitmap, draw_x - (bitmap.getWidth() / 2), draw_y - (bitmap.getHeight() / 2), null);
This is a typical operation to draw a background or a sprite. You can also use Canvas.drawText(), Canvas.drawRectangle(), Canvas.drawColor(). Lots of things.
I'm working on a game that uses Canvas as the main drawing surface, check out onDraw() in my MainGamePanel class and draw(Canvas) in my GameItem class for some examples of drawing various bitmaps/shapes/colors to a Canvas. Just remember every time you draw, you will overwrite what's below it, so the order of operations definitely matters.
Try this:
Use a SurfaceView.
Create a Bitmap from the texture (.jpeg file) with the values you found eg. screen size.
Draw that Bitmap to the canvas.
I hope this helps.
Related
Hello everyone I am new to android and I just have a quick question. I am making an animation using Bitmaps and drawing them to the canvas using the onDraw(). I am trying to draw a background to the canvas that I made in photoshop. I already uploaded it as a drawable and then decoded it to a Bitmap then added it to the onDraw method. It draws, but I doesn't fill the entire canvas like I want it to. Any suggestions and or fixes? Thank you so much, I looked around and saw something about converting the bitmap to an image view but didn't really understand all to well.
Use drawBitmap(Bitmap bitmap, Rect src, RectF dst, Paint paint) where the rect for source is the entire bitmap (from 0,0 to width, height) and dest is the entire canvas. This will stretch the bitmap to fill the canvas. Be warned this can cause the aspect ratio to be off and/or issues with fuzziness or blockiness.
Suppose, we've got a display sized 100x100, an image 100x50, and I want to enlarge that image so that it has the same height as the screen does. So the image will be 200x100. After that I want to make the animation of image movement to the left and to the right. I've found 2 ways of the realization of my task:
To create a new image using Bitmap.createScaledBitmap(). But the
image created this way will occupy twice more RAM.
To use matrix.setScale() in every onDraw(). But this works very
slow. Is there any other better solution?
The second method is slow because you calculate your "matrix" on every frame! Since your matrix is always the same thing and it does not change, you can pre-calculate your matrix and save it as a "field" in you class, then just use this function to draw it on screen:
canvas.drawBitmap(Bitmap bitmap, Matrix matrix, Paint paint)
It should be fast enough. The other option is to use:
canvas.drawBitmap(Bitmap bitmap, Rect src, RectF dst, Paint paint)
Again, try to pre-calculate stuff as much as possible. In this case, pre-calc src and dst rectangles.
I've created a simple custom control in android and on it I place a background image. I'm having problems when the control is placed on a layout at different sizes (i.e. when it is stretched), specifically:
I wish to overlay a rectangle at a specific position and size, which I know the pixel position for the original image. How can I do this with my control. I suspect something like this is impossible given it's a 9-patch. Is my best bet to work out the percentage from the top/left on the original or is that pointless given some parts stretch and some don't?
In the custom control I set the image like this in the constructor:
setBackgroundResource(R.drawable.buttonbt);
Which is working just fine, however I wanted to originally draw it in the onDraw event as I might want to change it depending on property changes, e.g.
Bitmap b=BitmapFactory.decodeResource(getResources(), R.drawable.buttonbt);
canvas.drawBitmap(b, 0, 0, null);
But this does not resize according to the size of its bounding box, it is simply trying to show it at it's original size without scaling to fit. How would you do this (whether the former method is better or not).
thanks.
You can create a scaled bitmap as below
Bitmap bitmap = Bitmap.createScaledBitmap(b, width, height, true);
Hope it will work for you. Please let me know!
ok when your View is say 100x100 px and your Bitmap is 300x300 you can try the following (pseudo code here) in inDraw method:
# src is a Bitmap 300x300
# dst is a View 100x100
mMatrix.setRectToRect(RectF src, RectF dst, Matrix.ScaleToFit stf)
canvas.save()
canvas.concat(mMatrix)
canvas.drawBitmap(mBitmap, 0, 0, null)
// actually it will draw a rect with left/top edge at (10, 10) and right/bottom at (20, 20)
canvas.drawRect(30, 30, 60, 60, paint)
canvas.restore()
I am trying to make an app using canvas and a surfaceview, and I am worrying that in the future I would have many problems with it because I am not sure if the canvas is proportional with every device. currently I can only use my emulator since my phone's usb cable doesn't work(I know.. I have to get a new one..).
anyways, i would like to know if the canvas would transfer my coordinates and make everything proportional, what I mean by that is that if i have something in point a, lets say (10, 10) on a device that the screen of it is 100 X 100 (this is just an example for easy calculation) it would be on point (1, 1) on a 10 X 10 device.
This is really bothering me...
Thanks!
No, this wouldn't be the case. If you have a coordinate (10,10), it would be the same on all devices. I'd suggest you scale your drawings.
To scale your drawings you simply define a bitmap (that will stay the same) you'd like to draw to (when screen sizes change, that bitmap will be stretched).
Define a constant bitmap:
Bitmap gameScreen = Bitmap.createBitmap(getGameScreenWidth(),
getGameScreenHeight(), Config.RGB_565);
Get the scale for both x and y
width = game.getWindowManager().getDefaultDisplay().getWidth();
height = game.getWindowManager().getDefaultDisplay().getHeight();
scaleXFromVirtualToReal = (float) width/this.gameScreenWidth;
scaleYFromVirtualToreal = (float) height/this.gameScreenHeight;
Define a canvas object based on the bitmap you defined earlier on (allowing you to draw to it eg. canvas.drawRect() [...]):
Canvas canvasGameScreen = new Canvas(gameScreen);
In your rendering Thread you'll have to have a Canvas called frameBuffer, which will render the virtual framebuffer:
frameBuffer.drawBitmap(this.gameScreen, null, new Rect(0, 0, width,
height), null);
No, the unit on the screen (whether you are using canvas or OpenGL) is a pixel. You can get the size of your canvas using Canvas.getWidth() and Canvas.getHeight() if you need relative coordinates, but your Canvas drawing methods are also in Pixels, so I guess you will need to convert coordinates in OpenGL only and not while using Canvas.
I have a widget which looks like this:
Every cone is a "touchable element". Now I want to put a bitmap texture above each cone. However, bitmap images are all rectangular, so a bitmap texture above one cone would interfere with the bitmap texture above another cone.
I'm wondering what is the best solution to this approach. Should I just create an image which fits (as a rectangle) exactly above the cone and make the non used areas transparent?
A second question is, how do bitmap textures work with stretching? Because this whole circle draws itself to fit the whole screen size, while bitmap textures are pretty much one size.
Offhand I can't think of a better way to draw bitmaps over those cones than your own suggestion of using transparent zones.
However, I can help with your second question as stretching bitmaps is not hard. You've got a few options in the Canvas class. For example:
canvas.save();
canvas.scale(xRatio, yRatio);
canvas.drawBitmap(....);
canvas.restore();
You can also use a Matrix, using matrix.postScale(xRatio, yRatio), to then generate either a larger bitmap and draw it normally, or pass the matrix in to your canvas.drawBitmap(....) command to make it scale while it draws.
All of these methods assume you have access to the drawing canvas itself. If you are using a view, you can subclass it and override the onDraw(Canvas canvas) method to grab the canvas before it starts drawing it. If you're using a SurfaceHolder, then you should already know how to get the canvas.
Edit: I forgot the third method I was going to describe. You can use the canvas.drawBitmap(bitmap, srcRect, dstRect, paint) to also make the canvas scale the bitmap to fit the destination rectangle. In short, there are lots of methods to do this - pick the one that's easiest based on your application!