Develop Reference

Draw text with a shape mask?

I am drawing text on a canvas. I would like to draw a solid circle of color over the text, and only have the circle be painted where it intersects the text. Example:
and what I want to do:
I'm not sure if this is possible, my draw code is simply:
public void onDraw(Canvas canvas) {
canvas.drawText("Hello", x, y, paint);
paint.setColor(orange);
canvas.drawOval(...);
}
I suppose I would need to apply some masking, but not sure how to get started.

follow this tutorial from a googler...
android-shaders-filters
BitmapShader may help you

You can use PorterDuffXfermode in Android to achieve this.
If you use below code it will work fine:
Bitmap original = Bitmap.createBitmap(canvas.getWidth(), canvas.getHeight(),
Bitmap.Config.ARGB_8888); // Created from Canvas
Bitmap mask =
Bitmap.createBitmap(getContext().getResources(),R.drawable.mask_image);
Bitmap result = Bitmap.createBitmap(mask.getWidth(), mask.getHeight(),
Config.ARGB_8888);
Canvas tempCanvas = new Canvas(result);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
tempCanvas.drawBitmap(original, 0, 0, null);
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
tempCanvas.drawBitmap(mask, 0, 0, paint);
paint.setXfermode(null);
canvas.drawBitmap(result, 0, 0, new Paint());
What does PorterDuff.Mode mean in android graphics.What does it do?

How to mask only certain parts of a bitmap in Android

I want to be able to use the following image to mask other bitmap. So basically, I'm trying to get the mask image and replace it's black content with another bitmap. Like this for example:
I'm able to use this mask and create a round version of the original bitmap, but that does not retain that orange border around it. Any thoughts on how I can accomplish this effect? Thanks.
The code that I am using (that only creates a round image) is the following:
private static Bitmap applyMask(ImageView imageView, Bitmap mainImage) {
Canvas canvas = new Canvas();
Bitmap result result = Bitmap.createBitmap(50, 50, Bitmap.Config.ARGB_8888);
canvas.setBitmap(result);
Paint paint = new Paint();
// resize image fills the whole canvas
canvas.drawBitmap(mainImage, null, new Rect(0, 0, 50, 50), paint);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
canvas.drawBitmap(sMaskImage, 0, 0, paint);
paint.setXfermode(null);
return result;
}

I use below code snipped to set masked images, this sample "bm" is my bitmap and "mMaskSource" is the resource id of mask object position in my drawable folder.
Bitmap mask = BitmapFactory.decodeResource(getResources(), mMaskSource);
Bitmap result = Bitmap.createBitmap(mask.getWidth(), mask.getHeight(),
Config.ARGB_8888);
Canvas mCanvas = new Canvas(result);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
bm = Bitmap.createScaledBitmap(bm, mask.getWidth(), mask.getHeight(),
true);
mCanvas.drawBitmap(bm, 0, 0, null);
mCanvas.drawBitmap(mask, 0, 0, paint);
paint.setXfermode(null);
And finally you can use "result" bitmap object however you wish.

Add water effect on bitmap android

How can i add water waves in bitmap image?
i have found water ripple effect on touch event here: https://github.com/esteewhy/whater but can not implement on my single bitmap.
can anyone help in making water wave effect on my bitmap?
or should i go for image processing?
Thank you in advance.
Here is my sample code in which i have to make water reflection effect:
public static Bitmap reflection(Bitmap mainImage) {
int width = mainImage.getWidth();
int height = mainImage.getHeight();
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
reflectionImage = Bitmap.createBitmap(mainImage, 0,
0, width, height , matrix, false);
reflectedBitmap = Bitmap.createBitmap(width,
(height + height), Config.ARGB_8888);
Canvas canvas = new Canvas(reflectedBitmap);
canvas.drawBitmap(mainImage, 0, 0, null);
Paint defaultPaint = new Paint();
canvas.drawRect(0, height, width, height, defaultPaint);
canvas.drawBitmap(reflectionImage, 0, height-6 , null);
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0,
mainImage.getHeight(), 0, reflectedBitmap.getHeight()
, 0x70ffffff, 0x00ffffff, TileMode.CLAMP);
paint.setShader(shader);
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
canvas.drawRect(0, height, width, reflectedBitmap.getHeight()
, paint);
return reflectedBitmap;
}

Add Watermark to an image just like flipboard in Android

I want to add watermark to images just like flipboard does.
As you can see text is added at the bottom of the images with black transparent background. I want to do the exact same thing. Till now I've managed to write text on image but I am not able to make it's background black transparent just like the above picture.
Here's my code so far which I found from here.
public Bitmap mark(Bitmap src, String watermark) {
int w = src.getWidth();
int h = src.getHeight();
Shader shader = new LinearGradient(0, 0, 100, 0, Color.TRANSPARENT, Color.BLACK, TileMode.CLAMP);
Bitmap result = Bitmap.createBitmap(w, h, src.getConfig());
Canvas canvas = new Canvas(result);
canvas.drawBitmap(src, 0, 0, null);
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setTextSize(50);
paint.setAntiAlias(true);
paint.setShader(shader);
paint.setUnderlineText(false);
canvas.drawText(watermark, 10 , h-15, paint);
return result;
}

I think it doesn't require gradient, you can draw it using simple color and using drawRect() method.
Sample code is below, i gonna take the black background size as 25% of whole image.
public Bitmap mark(Bitmap src, String watermark) {
int w = src.getWidth();
int h = src.getHeight();
Paint bgPaint=new Paint();
bgPaint.setColor(Color.parse("AA000000")); //transparent black,change opacity by changing hex value "AA" between "00" and "FF"
Bitmap result = Bitmap.createBitmap(w, h, src.getConfig());
Canvas canvas = new Canvas(result);
canvas.drawBitmap(src, 0, 0, null);
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setTextSize(50);
paint.setAntiAlias(true);
paint.setUnderlineText(false);
//should draw background first,order is important
int left=0;
int right=w;
int bottom=h;
int top=bottom-(h*.25);
canvas.drawRect(left,top,right,bottom,bgPaint);
canvas.drawText(watermark, 10 , h-15, paint);
return result;
}

Android : Constructing bitmap from RECT

Can we construct a bitmap from a rect.
I draw a bitmap in a rect and want strokes drawn on the bitmap image become part of the image.
I am wondering if I can construct a bitmap from a Rect so the new bitmap has the old image and the strokes as a single image.
Thank You

You can always take a canvas to help you create an already decoded bitmap the way you want:
Bitmap originalBmp = null;//Here goes original Bitmap...
ImageView img = null;//Any imageview holder you are using...
Bitmap modifiedBmp = Bitmap.createBitmap(100, 100, Bitmap.Config.ARGB_8888);//Configure with your proper size and color
Canvas canvas = new Canvas(modifiedBmp);
//At this point the modified bitmap has the original one, starting from here, you can add any overlay you want...
canvas.drawBitmap(originalBmp, 0, 0, new Paint());
//And do all the other modifications you want here...
canvas.drawLines(new float[]{}, null);
canvas.drawCircle(x, y, radius, null);
//At this point the modified bitmap will have anything you added
img.setImageBitmap(modifiedBmp);
// IF YOU ARE OVERRIDING ONDRAW METHOD
public void onDraw(Canvas canvas){
//Here DO your DRAW BITMAP NOTE: paint must be already created...
canvas.drawBitmap(bt, 0, 0, paint);
paint.setColor(Color.BLACK);
paint.setStrokeWidth(3);
canvas.drawRect(30, 30, 80, 80, paint);
super.onDraw(canvas);
}
Regards!

Yes you can , Using canvas you can draw something on your old bimtap .
Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),
bitmap.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff424242;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
paint.setAntiAlias(true);
canvas.drawARGB(0, 0, 0, 0);
paint.setColor(color);
// do some canvas drawing
canvas.drawBitmap(bitmap, rect, rect, paint);