Develop Reference

Drawing bitmap to the size of the canvas

I have bitmap that need to draw to canvas. The image is of a fixed size, but the canvas will change according to the user's screen size and density (bitmap coule be larger/smaller than the canvas).
I need to draw the bitmap to canvas scaling all the way into the canvas size (without distorting the image), I have done the code as below but the bitmap still filling only a portion of the screen.
Rect dest = new Rect(0, 0, drawCanvas.getWidth(), drawCanvas.getHeight());
Paint paint = new Paint();
paint.setFilterBitmap(true);
drawCanvas.drawBitmap(canvasBitmap, null, dest, paint);
May I know if anybody can shed light on a good solution? Thanks.

This example is in javascript but it should still help you out scale an image
jsFiddle : https://jsfiddle.net/CanvasCode/7oghuwe2/3/
javascript
var canvas1 = document.getElementById('canvas1');
var context1 = canvas1.getContext('2d')
var canvas2 = document.getElementById('canvas2');
var context2 = canvas2.getContext('2d');
var image1 = new Image();
image1.src = "http://media.giphy.com/media/iNk83OBPzlA8o/giphy.gif";
image1.onload = function () {
context1.fillStyle = "#F00";
context1.fillRect(0, 0, canvas1.width, canvas1.height);
context2.fillStyle = "#00F";
context2.fillRect(0, 0, canvas2.width, canvas2.height);
ratio(context1, canvas1, image1);
ratio(context2, canvas2, image1);
}
function ratio(context1, canvas1, image1) {
var imageRatio = image1.width / image1.height;
var newHeight = canvas1.width / imageRatio;
var newWidth = canvas1.height * imageRatio;
var heightDiff = newHeight - canvas1.height;
var widthDiff = newWidth - canvas1.width;
if (widthDiff >= heightDiff) {
context1.drawImage(image1, 0, 0, canvas1.width, canvas1.width / imageRatio);
} else {
context1.drawImage(image1, 0, 0, canvas1.height * imageRatio, canvas1.height);
}
}
Basically you need to calculate what the width would be if you scaled the image by the canvas height and what the height would be if you scale the image by the canvas width, and which ever is smaller, then you scale by that dimension.

The reason why it might not work for you might be because the function drawBitmap() ignores the density of the bitmap. The following is from the documentation.
public void drawBitmap (Bitmap bitmap, Rect src, Rect dst, Paint
paint)
This function ignores the density associated with the bitmap. This is
because the source and destination rectangle coordinate spaces are in
their respective densities, so must already have the appropriate
scaling factor applied.
What you could do is use public void drawBitmap (Bitmap bitmap, Matrix matrix, Paint paint) instead. First you need to map the source Matrix with the desination Matrix. You do this via Matrix.setRectToRect() or Matrix.setPolyToPoly(). This will give you an accurate mapping. Just make sure you map them correctly, otherwise things will be distorted.
For more info refer here: What code should I use with 'drawMatrix.setPolyToPoly' to manipulate and draw just a rectangular part of a bitmap, rather than the entire bitmap?

Water reflection effect on bitmap

I trying to achieve water reflection effect on bitmap. As I saw some apps called water reflection. I know how to do the reflection of the image but the wave on the image is what making me confused on how it is done.
see this image for example
I did many apps on bitmap manipulation but this is quite hard to achieve.
So any idea on where to start. Just an idea to start can be helpful.

For any one needed, I tried some simple tricks to get as closer as water reflection effect. It is not great but it looks fine to me.
I used two methods
Bitmap reflection method (give bitmap as a parameter)
public static Bitmap Reflection(Bitmap imageBitmap) {
int width = imageBitmap.getWidth();
int height = imageBitmap.getHeight();
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
Bitmap reflectionImage = Bitmap.createBitmap(imageBitmap, 0,
0, width, height , matrix, false);
Bitmap newbit=Bitmap.createScaledBitmap(reflectionImage, reflectionImage.getWidth()/8, reflectionImage.getHeight()/8, true);
Bitmap newbit1=Bitmap.createScaledBitmap(newbit, newbit.getWidth()*8, newbit.getHeight()*8, true);
Bitmap scalednew=Bitmap.createScaledBitmap(newbit1, width, height-(height/4), true);
Bitmap newscaledone=overlay(scalednew);
reflectionImage=newscaledone;
Bitmap reflectedBitmap = Bitmap.createBitmap(width,
(height + height), Config.ARGB_8888);
Canvas canvas = new Canvas(reflectedBitmap);
canvas.drawBitmap(imageBitmap, 0, 0, null);
Paint defaultPaint = new Paint();
canvas.drawRect(0, height, width, height, defaultPaint);
canvas.drawBitmap(reflectionImage, 0, height , null);
Paint paint = new Paint();
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
canvas.drawRect(0, height, width, reflectedBitmap.getHeight()
, paint);
return reflectedBitmap;
}
Bitmap overlay method. I am taking a wave bitmap with some opacity to overlay on the reflected image. So that it may look like water.
Bitmap wavebitmap=BitmapFactory.decodeResource(getResources(), R.drawable.waves1);
private static Bitmap overlay( Bitmap bmp2) {
Bitmap bmp1=WaterReflectionMainActivity.wavebitmap;
Bitmap bmp1new =Bitmap.createScaledBitmap(bmp1, bmp2.getWidth(), bmp2.getHeight(), true);
Bitmap bmOverlay = Bitmap.createBitmap(bmp1new.getWidth(), bmp1new.getHeight(), bmp1new.getConfig());
Canvas canvas = new Canvas(bmOverlay);
canvas.drawBitmap(bmp2, new Matrix(), null);
canvas.drawBitmap(bmp1new, new Matrix(), null);
return bmOverlay;
}
Well this is my version of water effect, I know this looks shit.
So if anyone still got some better effect please share your code .
thank you

Tutorial related to this: http://www.xaraxone.com/webxealot/workbook34/page_4.htm
Also have a read at this question: Add water effect on bitmap android.
Have a read at both of them, i hope you will get an idea from this
You may also want to look through these: 1, 2, 3

This is just an idea but basically, what you need is to apply a deformation on the bottom part of the image, meaning that for each pixel on the bottom half, you compute a position to get it's color from the top picture.
Here's a pseudo code to give you a hint :
for (int x = 0; x < width; x++) {
for (int y = 0; y < img.height; y++) {
// Compute a position on the original image
// tweak the values heres to get the effect you want
sourceX = x + (int) (cos(10000.0 / y) * 20);
sourceY = img.height - y - 1 +(int)( sin(y* 0.5) * 20);
// Maybe check the range of sourceX and source Y
int color = img.getColor(sourceX, sourceY)
outptut.setColor(x, y + img.height, color);
}
}

you can achieve this by masking may this code will help you
http://www.seeques.com/22527681/how-can-do-this-effect-in-android-may-be-android-bitmap-masking-effect.html
EDIT
also see this for reference
http://code.google.com/p/android-ripple-demo/source/browse/#svn%2Ftrunk%2Fsrc%2Fcom%2Fkesalin%2FRippleDemo
https://github.com/esteewhy/whater
http://code.google.com/p/waterrippleeffect/source/browse/trunk/src/com/example/android/watereffect/WaterEffectView.java?r=3
android noise effect on bitmap

Android Cover Flow with image shadow effect

I want to implement cover flow as below
I have tried Carousel, but its not the same thing. Did some google search was not able to find something even near to the cover flow implemented in given example.

Definitely have a look at this, FancyCoverFlow.
There is a demo app for it in the Play store as well that shows the reflection requirement you'd like.

have you tried this:
blog post
public Bitmap getRefelection(Bitmap image) {
// The gap we want between the reflection and the original image
final int reflectionGap = 0;
// Get you bit map from drawable folder
Bitmap originalImage = image;
int width = originalImage.getWidth();
int height = originalImage.getHeight();
// This will not scale but will flip on the Y axis
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
// Create a Bitmap with the flip matix applied to it.
// We only want the bottom half of the image
/*if(bitmapWithReflection!=null && !bitmapWithReflection.isRecycled()){
bitmapWithReflection.recycle();
bitmapWithReflection=null;
}*/
Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,
height / 2, width, height / 2, matrix, false);
// Create a new bitmap with same width but taller to fit reflection
Bitmap bitmapWithReflection = Bitmap.createBitmap(width,(height + height / 2), Config.ARGB_8888);
// Create a new Canvas with the bitmap that's big enough for
// the image plus gap plus reflection
Canvas canvas = new Canvas(bitmapWithReflection);
// Draw in the original image
canvas.drawBitmap(originalImage, 0, 0, null);
//Draw the reflection Image
canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
// Create a shader that is a linear gradient that covers the reflection
Paint paint = new Paint();
LinearGradient shader = new LinearGradient(0,
originalImage.getHeight(), 0, bitmapWithReflection.getHeight()
+ reflectionGap, 0x40ffffff, 0x00ffffff, TileMode.CLAMP);
// Set the paint to use this shader (linear gradient)
paint.setShader(shader);
// Set the Transfer mode to be porter duff and destination in
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
// Draw a rectangle using the paint with our linear gradient
canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
+ reflectionGap, paint);
if(originalImage!=null && originalImage.isRecycled()){
originalImage.recycle();
originalImage=null;
}
if(reflectionImage!=null && reflectionImage.isRecycled()){
reflectionImage.recycle();
reflectionImage=null;
}
return bitmapWithReflection;
}

Have you gone through the Android Coverflow which is bit different form the Carousel which you want.

I made cover flow widget which is not dependent on gallery.
You can find it here. I will add some samples later.
http://applm.github.io/ma-components/

Display a specific area of a Bitmap in imageView

Here is my issue, I display in a ListView some Pictures come from web.
I would like to display in my ImageView only a specific area to my picture, without resizing it.
Here is a concret example :
https://docs.google.com/file/d/0B6J9AVdWXjwuWld5dU5CWXFSTjQ/edit?usp=sharing
I think it's possible with a Bitmap method, but I really don't know how to do this...
Thanks for your tips

Yes, the way to do this is to create a Bitmap object out of your source image. Here's an example:
File thumbFile = new File(thumbFileDir, imageName);
//Bitmap source = your image
Bitmap target= Bitmap.createBitmap(thumbSize, thumbSize,Config.ARGB_8888); //in my case the thumb image is square, use your dimensions instead of "thumbSize, thumbSize"
Canvas canvas = new Canvas(target);
float hScale = thumbSize/(float)source.getWidth(); //again, thumb dimensions here
float vScale = thumbSize/(float)source.getHeight(); //and here
float scale = Math.max(hScale, vScale);
Matrix matrix = new Matrix();
matrix.setScale(scale, scale);
matrix.postTranslate(thumbSize/2 - source.getWidth()/2 * scale, thumbSize/2 - source.getHeight()/2 * scale); //and here
canvas.drawColor(Color.BLACK);
canvas.drawBitmap(source, matrix, new Paint());
The "target" object is what you are asking for

Show portion of Bitmap image on canvas in Android

I am trying to build a Magnify tool in my Android app. For this, I have an ImageView, which I converted to Bitmap (with some zoom/scale factor).
imageView.setDrawingCacheEnabled(true);
Bitmap drawingCache = imageView.getDrawingCache(true);
Matrix matrix = new Matrix();
matrix.postScale(5, 5);
Bitmap viewCapture = Bitmap.createBitmap(drawingCache, 0, 0,
drawingCache.getWidth(),
drawingCache.getHeight(),
matrix, true);
imageView.setDrawingCacheEnabled(false);
Now, I am drawing this Bitmap image "viewCapture" to my canvas. Here, I want only portion of the image to be rendered on the canvas.
I tried using approaches: "setRectToRect() on Matrix", "canvas.drawBitmap(bitmap, src, dst, paint)". But, didn't work out appropriately.
Would using SurfaceViews be helpful? Has anyone come across this situation? Please post your thoughts/ideas.

Why not just use the following?
Canvas.drawBitmap(Bitmap bitmap, Rect src, RectF dst, Paint paint)
src corresponds to which region of the bitmap you want to draw and dst says where you want the bitmap drawn. You can read more about it here: http://developer.android.com/reference/android/graphics/Canvas.html

When I do that, I get a smaller image of the bitmap, instead of cropped image. Following is the snippet I have used.
Canvas c = holder.lockCanvas();
c.drawRGB(10, 10, 10);
Rect src = new Rect((int)x - _image.getWidth(), (int) y - _image.getHeight(), (int)x + _image.getWidth(), (int) y + _image.getHeight());
RectF dst = new RectF((int)x - 50, (int) y - 50, (int)x + 50, (int) y + 50);
c.drawBitmap(_image, src, dst, null);
holder.unlockCanvasAndPost(c);