I have this code snippet. I don't understand the Matrix.preScale and the Bitmap.createBitmap with the matrix passed. What does it mean? Is there any simulation website to understand matrix calculation? Could you give me some websites about mathematics used for graphics? I'm sorry I'm not good at mathematics. :)
public Bitmap createReflectedImages(final Bitmap originalImage) {
final int width = originalImage.getWidth();
final int height = originalImage.getHeight();
final Matrix matrix = new Matrix();
matrix.preScale(1, -1);
final Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, (int) (height * imageReflectionRatio),
width, (int) (height - height * imageReflectionRatio), matrix, false);
final Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (int) (height + height * imageReflectionRatio + 400),
Config.ARGB_8888);
final Canvas canvas = new Canvas(bitmapWithReflection);
canvas.drawBitmap(originalImage, 0, 0, null);
final Paint deafaultPaint = new Paint();
deafaultPaint.setColor(color.transparent);
canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);
final Paint paint = new Paint();
final LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0,
bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff, TileMode.CLAMP);
paint.setShader(shader);
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
canvas.drawRect(0, height, width, bitmapWithReflection.getHeight() + reflectionGap, paint);
return bitmapWithReflection;
}
Don't think about it too hard, at least not at the early stages.
Just think of a matrix as an array of numbers. In this case, an Android Matrix has 3 rows of 3 numbers. Each number tells an Android graphics function what to do to scale (bigger/smaller), translate (move), rotate (turn) or skew (distort in a 2D plane) the "thing" which the matrix is applied to.
The matrix looks like this (see the docs here).
{Scale X, Skew X, Transform X
Skew Y, Scale Y, Transform Y
Perspective 0, Perspective 1, Perspective 2}
The good news is that you don't need to know any matrix maths, indeed almost no maths, to use matrices in Android. That's what methods like preScale() do for you. To understand the maths behind is not that hard, for most things you only need add, multiply and SOHCAHTOA.
matrix-transform-for-the-mathematically-challenged/
When you read the Matrix documentation, you will see methods for rotate, translate etc with prefixes of 'set', 'post' or 'pre'.
Imagine that you create a new matrix. You then use setRotate() to setup the matrix to do a rotation. You then use preTranslate() to do a translation. Because you used 'pre', the translation happens before the rotation. Had you used 'post', the rotation would happen first. 'set' clears whatever is in the matrix and starts again.
To answer your specific question, new Matrix() creates the 'identity matrix'
{1, 0, 0
0, 1, 0
0, 0, 1}
which scales by 1 (therefore same size) and does no translation, rotation or skew. Therefore, applying the identity matrix will do nothing. The next method is preScale() which is applied to this identity matrix and in the case you've shown, results in a matrix that scales, and does nothing else so could also be done using setScale() or postScale().
Related
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
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/
I have tried several hours to rotate a bitmap with no success. I have read numerous articles about this subject on this web site and it seems the prefered solution involves creating a temporary canvas. Well I did this and I still do not see a roated bitmap.
My bitmap is a 40x40 blue square and I am trying to rotate it 45 degrees. Thats not asking for much is it? When the code runs, the bitmap that appears on the screen is the non-rotated original. ( I have also tried a translate with no success as well)
Here is my code:
// Load the bitmap resource
fillBMP2 = BitmapFactory.decodeResource(context.getResources(), R.drawable.test1);
// Copy to a mutable bitmap
mb = fillBMP2.copy(Bitmap.Config.ARGB_8888, true);
// Create canvas to draw to
Canvas offscreenCanvas = new Canvas (mb);
// Create Matrix so I can rotate it
Matrix matrix = new Matrix();
matrix.setRotate (45);
offscreenCanvas.setMatrix (matrix);
// Send the contents of the canvas into a bitmap
offscreenCanvas.setBitmap(mb);
Later in an OnDraw I do the following:
canvas.drawBitmap(mb, 200, 200, null);
Any ideas what I am doing wrong? Seems like it should work.
Thanks
Try using this
Matrix matrix = new Matrix();
matrix.setRotate(15);
canvas.drawBitmap(bmp, matrix, paint);
setRotation method takes in a float representing
the degrees of rotation.
Try this...
Matrix matrix = new Matrix();
float px = 200;
float py = 200;
matrix.postTranslate(-bitmap.getWidth()/2, -bitmap.getWidth()/2);
matrix.postRotate(45);
matrix.postTranslate(px, py);
canvas.drawBitmap(bitmap, matrix, paint);
You definitely want to use transformations: check out this link.
Basically it's this:
// save the canvas
ctx.save();
// move origin to center
ctx.translate(x,y);
// rotate
ctx.rotate(angle * (Math.PI / 180));
// draw image
ctx.drawImage(image, x, y, w, h, .w/2, h/2, w, h);
// restore
ctx.restore();
I am trying to create an Oval Bitmap and I need to get a feather effect around the margins,
Does anyone have any idea How I can achieve this ?
Thanks.
You could consider the 'feather effect' as a gradial gradient, with the alpha fading from 100% to 0%.
Android offers the RadialGradient class for this purpose. You'll want to use the constructor where you can specify the control points for the radient, as you'll want the fading to start near the edge, not in the middle.
The one problem with Android's RadialGradient class is that it only supports perfect circles, not for ovals. To compensate for this, we'll just draw a perfect circle and scale afterwards.
Example code:
private Bitmap makeFeatheredOval(int width, int height) {
// Determine largest dimension, use for rectangle.
int size = Math.max( width, height);
RadialGradient gradient = new RadialGradient(size / 2, size / 2, size / 2,
new int[] {0xFFFFFFFF, 0xFFFFFFFF, 0x00FFFFFF},
new float[] {0.0f, 0.8f, 1.0f},
android.graphics.Shader.TileMode.CLAMP);
Paint paint = new Paint();
paint.setShader(gradient);
Bitmap bitmap = Bitmap.createBitmap(size, size, Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
canvas.drawCircle(size / 2, size / 2, size / 2, paint);
// Scale the bitmap, creating an oval
bitmap = Bitmap.createScaledBitmap(bitmap, width, height, true);
return bitmap;
}
Example image (it's the oval "moon" in the upper left corner):
Bonus points for everyone who recognizes that backdrop image.
I'm trying to rotate an image around the center. This works generally using RotateAnimation, but I want to have it a bit faster. I'm now using the SurfaceView pattern with a separate drawing thread.
This is code, which draws the bitmap correctly (depending on the outer "heading")
heading = angle in degrees,
bitmap = the bitmap,
w = width of the bitmap,
h = height of the bitmap.
Matrix m = new Matrix();
m.preRotate(heading, w/2, h/2);
m.setTranslate(50,50);
canvas.drawBitmap(bitmap, m, null);
Drawback: The image is a circle and the code above produces visible aliasing effects...
The code below is also rotating the image, but while rotating (say from 0 to 45 degrees clockwise) the center of the new image moves bottom/right. I suppose, the eccentric effect is due to the enlarged width/height of the new image ?? However, this code doesn't produce aliasing, if filter=true is set. Is there a way to use code #1 but have sort of anti-aliasing or use code #2 but getting rid of the center movement?
Matrix m = new Matrix();
m.preRotate(heading, w/2, h/2);
m.setTranslate(50,50);
Bitmap rbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, m, true);
canvas.drawBitmap(rbmp, 50, 50, null);
UPDATE: As result of the discussion in this thread the correct version of code #2 (anti-aliasing and correct rotation) would look like this (offset of 50,50 omitted):
Matrix m = new Matrix();
m.setRotate(heading, w/2, h/2);
Bitmap rbpm = Bitmap.createBitmap(bitmap, 0, 0, w, h, m, true);
canvas.drawBitmap(rbpm, (w - rbpm.getWidth())/2, (h - rbpm.getHeight())/2, null);
Thanks.
Find the center of the original image and for the new image and center using that:
Matrix minMatrix = new Matrix();
//height and width are set earlier.
Bitmap minBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas minCanvas = new Canvas(minBitmap);
int minwidth = bitmapMin.getWidth();
int minheight = bitmapMin.getHeight();
int centrex = minwidth/2;
int centrey = minheight/2;
minMatrix.setRotate(mindegrees, centrex, centrey);
Bitmap newmin = Bitmap.createBitmap(minBitmap, 0, 0, (int) minwidth, (int) minheight, minMatrix, true);
minCanvas.drawBitmap(newmin, (centrex - newmin.getWidth()/2), (centrey - newmin.getHeight()/2), null);
minCanvas.setBitmap(minBitmap);