I have a question about drawBitmap.
android.graphics.Canvas.drawBitmap(Bitmap bitmap, float left, float top, Paint paint)
What does that Paint paint? For example I have a picture.jpg and I make
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.picture);
paint = new Paint();
paint.setColor(Color.BLUE);
canvas.drawBitmap(bitmap, 0, 0, paint);
What can I do with that "paint" when I have a real picture not some canvas.drawCircle. Is there any way I can change pictures color or something like that?
Yes and another question. For example I draw circle in mspaint in 80x80 size and my background stays plain white. When I use that drawing in my program it shows circle + that white background. Is there any way that there will be displayed only circle without background. Maybe somebody can suggest some program in which I can make that happen or which code should I use in my program? (circle is just example, there can be anything)
Yes and excuse to use circle's background same as program's background is not appropriate, because my program's background isn't white or black or any other color, it is picture.
Paint objects can affect the rendering of the Bitmap. For example, they be used to mask the drawing of the Bitmap.
Save your circle as a PNG or GIF, and set the background as transparent (I do not know if MS Paint can do this).
i suggest gimp for image editing with transparency.
start a new image, delete the default layer, add a transparent layer, then paste your image over that. you can use the fuzzy select tool to trim any white space, then save as .png and you have a transparent image!
Related
I am trying to create a Black screen with a transparent Hole in the middle of the screen. Here is what i have tried.
#Override
public void draw(Canvas canvas)
{
Paint myPaint = new Paint();
myPaint.setColor(0xC0000000);
canvas.drawRect(mBlackRect, myPaint);
myPaint = new Paint();
myPaint.setColor(Color.TRANSPARENT);
myPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
canvas.drawRect(mTransparentRect, myPaint);
}
The second paint, shows black color instead of transparent. How can i punch a transparent hole in MY SemiBlack Canvas?
you didn't save the canvas, try the code below
Paint myPaint = new Paint();
int sc = canvas.saveLayer(mBlackRect.left, mBlackRect.top,
mBlackRect.right, mBlackRect.bottom, myPaint,
Canvas.ALL_SAVE_FLAG);
myPaint.setColor(0xC0000000);
canvas.drawRect(mBlackRect, myPaint);
myPaint.setColor(Color.TRANSPARENT);
myPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
canvas.drawRect(mTransparentRect, myPaint);
myPaint.setXfermode(null);
canvas.restoreToCount(sc);
You can not really "punch" a hole by "removing pixels" from something already drawn, at least not with a hardware layer. And if you use a software layer, it will be bad for performance.
What you want to do is draw your shape with an alpha mask applied to your paint. A mask will prevent some parts of the shape to be drawn on the canvas, like cutting a piece of paper and stick it on a wall before spreading the painting.
To apply an alpha mask to your paint, you first need to create a bitmap containing the "hole" shape (programmatically or by loading a custom image from resources), then create a BitmapShader from this bitmap with the proper Xfermode (depending if you want the transparent part in your mask bitmap to be cut out or the non-transparent part) and finally apply this shader to your paint before drawing the semitransparent rectangle or anything you want.
Be careful with performance: only create the Paint object once (do not allocate any object in onDraw() because this method gets called up to 60 times per second on the UI thread), and recreate the alpha mask bitmap only when the bounds of your View/Drawable change (if its dimensions depend on the View dimensions of course, otherwise you just create it once).
I'm sorry if I don't have time to give you ready-to-use code but I think you should find plenty of information about the technique I just described and you can start experimenting and figuring out the solution by yourself which is more rewarding I think ;)
Imagine that I have a rectangle image. How could I create a style like the next one?
I mean, cropping the image into a circle, add the border, the shadow and the gross /shine effect. Until now, I only have tried this snippet code to crop the image: Cropping circular area from bitmap in Android but just that. I have no idea how to do the remaining components in Android.
An easy way to achieve this effect is to use Canvas.drawCircle() and a BitmapShader:
BitmapShader s = new BitmapShader(myPhoto, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
Paint p = new Paint();
p.setShader(s);
myCanvas.drawCircle(centerX, centerY, radius, p);
To do the shadow, simply call Paint.setShadowLayer() on the paint (this will only work if you draw the effect into an offscreen Bitmap or if your View uses a software layer – set by calling View.setLayerType() –).
The border can be drawn by drawing another circle on top, using the Paint.Style.STROKE style (that you can set by calling Paint.setStyle()).
Finally you can draw the gloss by drawing a circle, oval or Path on top of your very first circle. You'll need to use a LinearGradient shader on your paint and you'll also need to clip the gloss. You can do this in two ways:
If you are drawing the entire effect into a Bitmap, which is what I would recommend, simply set the paint's Xfermode to a new PorterDuffXfermode(PorterDuff.Mode.SRC_IN).
If you are drawing the effect directly on screen you can simply use Canvas.clipPath() to set a circular clip. Note that this will work with hardware acceleration only as of Android 4.3.
I want to make in my app possibilty to draw circles by user. The drawing is quite simple - user just press on canvas somewhere and then predefined circle
The difficult part here is to draw it with some drawable (picture) as a fill. It is quite simple when it is about rectangle. Then you just need to write:
Drawable drawable = getResources().getDrawable(R.drawable.my_background_picture);
drawable.setBounds(myRectangle);
drawable.draw(myCanvas);
Everything is done on onDraw() method of my custom view.
Unfortunatelly there isn't such simple method to make it with circle. The one that I've found is slight modification from Vogella's tutorial:
InputStream resource = getResources().openRawResource(R.drawable.sand);
Bitmap bitmap = BitmapFactory.decodeStream(resource);
BitmapShader shader;
shader = new BitmapShader(bitmap, Shader.TileMode.CLAMP,Shader.TileMode.CLAMP);
paint = new Paint();
paint.setAntiAlias(true);
paint.setShader(shader);
myCanvas.drawRoundRect(myRectangle, 120, 120, paint);
At first sight it looks ok, but it's not. This commands make just something like frame on a picture below, so you move hollow circle on a picture and that's all. Not as with rectangle where you actually move rectangular bitmap.
So, my question is - Is there a way to make circle drawable that can be also moved/resized?
Why make a drawable? You can easily draw a circle via the canvas.drawCircle command. You can also easily make one via a Path object.
Edit:
If you need a drawable, try making a ShapeDrawable based off an OvalShape.
I have an 8x8 Image. (bitmap - can be changed)
What I want to do is be able to draw a shape, given a Path and Paint object onto my SurfaceView.
At the moment all I can do is fill the shape with solid colour. How can I draw it with a pattern.
In the image you can see the brush pattern (The cross). It can be anything from a cross to a donut or an elf.
How would I go about drawing this pattern background.
I also eventually want to apply colours to it.
So far, my theory is to create a clip area of the shape, and tile the bitmaps until area is covered, but this is extreme overkill in processing. Nor sound ideal.
In terms of colouring, I can edit the brushes to be alpha, fill the same with background colour, then draw the images on top. The real issue it the tiling of such patterns.
Ive found a few questions of a similar nature, all unanswered, and/or not applicable to my situation. (use of xmls on views etc)
Did you checked this blog. Its using BitmapShader
Example:
//Initialize the bitmap object by loading an image from the resources folder
fillBMP = BitmapFactory.decodeResource(m_context.getResources(), R.drawable.cross);
//Initialize the BitmapShader with the Bitmap object and set the texture tile mode
fillBMPshader = new BitmapShader(fillBMP, Shader.TileMode.REPEAT, Shader.TileMode.REPEAT);
fillPaint.setStyle(Paint.Style.FILL);
//Assign the 'fillBMPshader' to this paint
fillPaint.setShader(fillBMPshader);
//Draw the fill of any shape you want, using the paint object.
canvas.drawCircle(posX, posY, 100, fillPaint);
I want to create a little scratch game. The problem is, that I can't figure out how to erase pixels from an image in android (like the eraser in gimp / photoshop).
The image is an .png with alpha channel.
AIUI, drawing operations on a canvas blend a transparent pixel with the prior value of the pixel. This is by default, and you can see it by setting a canvas to black and drawing a fully transparent shape onto it, and then drawing the underlying bitmap over an image of another canvas (result: a fully black canvas), or by setting a canvas to a partially transparent color and, drawing a shape of another partially transparent color, and then drawing this over an image (result: the original image is tinted by the first color, outside the shape; within the shape, it's tinted by both transparent colors). I don't know the blending method used by default, and looking through the docs just makes me wish I knew what book to buy so I can understand how to use what's available.
So I would set pixels to transparent by setting them 'directly', with Bitmap methods, rather than with canvas operations. Although if you need to punch a transparent shape into an overlay, you can draw the shape with a solid non-transparent color, and then manipulate the bitmap directly, mapping this color to the transparent color.
Bitmap docs. Prefer getPixels() and setPixels() to a method-call per pixel.
EDIT: ...er, did I misunderstand? You want to 'erase' pixels as in a paint program? Then just draw whatever the background color is. There's no erasure involved.