I've got a strange problem with Bitmap rotation.
That's my code:
in onDraw method
int cx_gear_big = (getWidth() - gear_big.getWidth()) >> 1;
int cy_gears_big = (getHeight() - gear_big.getHeight()) >> 1;
canvas.drawBitmap(rotateGear(gear_big, bigGearAngle), cx_gear_big,cy_gears_big, null);
That's my method which returns rotated Bitmap:
public static Bitmap rotateGear(Bitmap source, int angle)
{
Matrix matrix = new Matrix();
matrix.postRotate(angle);
return Bitmap.createBitmap(source, 0, 0, source.getWidth(), source.getHeight(), matrix, true);
}
I have few gears in my canvas, but it doesn't really matter.
My problem is:
When I'm rotating my Bitmap (a gear) it moves down and left (it depends on the angle of rotation) then it comes back...
Where can my problem be in this case?
UPD:
Translation of Bitmap is not linear. It's like bouncing.
So ideal way to solve this problem is translate matrix before rotation and translate it back. Code example:
Matrix m = new Matrix();
float px = getWidth()/2;
float py = getHeight()/2;
m.postTranslate(-bitmap.getWidth()/2, -bitmap.getHeight()/2);
m.postRotate(angle);
m.postTranslate(px, py);
canvas.drawBitmap(bitmap, m, null);
Just use this code
matrix.setRotate(angle, bitmap.getWidth()/2, bitmap.getHeight()/2);
Related
I am struggling with bitmap rotations. I wish to rotate a graphic around an alternate axis but I can only ever get it to rotate around the center point no matter what I do, putting in postTranlate. preTranslate, set Translate in any order doesnt work I have also tried the postRotate(45,0,0) but it always rotates around the center.
Code below taken of internet what would I do to alter its rotation point, the code below uses the launcher icon which is square I am using a long thin graphic like an arrow.
// Rotate image to 45 degrees.
public void RotateImage(){
ImageView image;
Bitmap bMap;
Matrix matrix;
//Get ImageView from layout xml file
image = (ImageView) findViewById(R.id.imageView1);
//Decode Image using Bitmap factory.
bMap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
//Create object of new Matrix.
matrix = new Matrix();
//set image rotation value to 45 degrees in matrix.
matrix.postRotate(45);
//Create bitmap with new values.
Bitmap bMapRotate = Bitmap.createBitmap(bMap, 0, 0,
bMap.getWidth(), bMap.getHeight(), matrix, true);
//put rotated image in ImageView.
image.setImageBitmap(bMapRotate);
}
I have tried the code below but its still rotates around the center or at least appears too
public void RotateImage{
ImageView image;
Bitmap bMap;
Matrix matrix;
//Get ImageView from layout xml file
image = (ImageView) findViewById(R.id.imageView);
//Decode Image using Bitmap factory.
bMap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
//Create object of new Matrix.
matrix = new Matrix();
//set image rotation value to 45 degrees in matrix.
matrix.setTranslate(-100,-200);
matrix.postRotate(angle);
matrix.postTranslate(100,200);
//Create bitmap with new values.
Bitmap bMapRotate = Bitmap.createBitmap(bMap, 0, 0,
bMap.getWidth(), bMap.getHeight(), matrix, true);
//put rotated image in ImageView.
image.setImageBitmap(bMapRotate);
Thanks
If you want your Bitmap to rotate 45 degree around x axis with pivot (a,b), you can call matrix.rotate(45, a, b)
Perhaps you want to use the Camera class to rotate around X, Y or Z axis:
matrix = new Matrix();
Camera camera = new Camera();
camera.save();
camera.rotateX(45f);
camera.getMatrix(matrix);
camera.restore();
The way I understand your question is that you want to rotate the image around some point, say (x, y). Conceptually you need to perform the following transformations on the image:
Translate by (-x, -y)
Rotate by 45 degrees
Translate by (x, y)
You can use this method to rotate an object from center create this method in sprite class
public void paintFromCenter(float angle, Canvas c) {
Bitmap b = sprite;
Bitmap h = b;
// Canvas canvas = new Canvas(a);
Matrix matrix = new Matrix();
matrix.postRotate(angle, h.getWidth() / 2, h.getHeight());
matrix.postTranslate(getX(), getY());
// canvas.drawBitmap(bitmap, matrix, new Paint());
Bitmap bmp2 = Bitmap.createBitmap(h, 0, 0, frameWidth, frameHeight,
matrix, true);
c.drawBitmap(h, matrix, null);
// g.getCanvas().drawBitmap(bmp2, getX(), getY(), null);
}
Now in onTouchEvent()
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_MOVE) {
evX = (int) event.getX();
evY = (int) event.getY();
int initX = objectSprite.getX();
int inity = objectSprite.getY();
if ((evX > objectSprite.getX()
&& evX < objectSprite.getX() + objectSprite.getWidth()
&& evY > objectSprite.getY() && evY < objectSprite.getY()
+ objectSprite.getHeight())) {
if (angle < 90) {
angle += 5;
} else if (angle < -180)
angle -= 5;
}
}
return true;
}
in draw() method paint the image/object
private void draw(Canvas canvas) {
objectSprite.paintFromCenter(angle, canvas);
}
try it
I have two ImageView/Bitmap, one for visible background and it not movable one, Another one is movable bitmap on the background view. The movable bitmap have pinch zoom and rotate with matrix. Finally find movable co-ordinates/rect position and crop background bitmap using those rect position. My question is how to calculate/get rect position?.
For my sample, what i need for your view. Pleas post your idea here, it help to every one.
I spend more time to search and after few weeks for get this result.
private Bitmap getCroppedBmp(Bitmap childBmp, Bitmap ParentBmp) {
// viewBmp is movable bitmap, orgBitmap is Parent Bitmap
Bitmap viewBmp = childBmp;
Bitmap orgBitmap = ParentBmp;
float[] v = new float[9];
// get Matrix from View
cropImage.savedMatrix.getValues(v);
float left = v[Matrix.MTRANS_X];
float top = v[Matrix.MTRANS_Y];
// calculate the degree of rotation
float rAngle = Math.round(Math.atan2(v[Matrix.MSKEW_X],
v[Matrix.MSCALE_X]) * (180 / Math.PI));
// Rotate viewBmp
Matrix m = new Matrix();
m.postRotate(rAngle, viewBmp.getWidth() / 2, viewBmp.getHeight() / 2);
Bitmap bmap = Bitmap.createBitmap(viewBmp, 0, 0, viewBmp.getWidth(),
viewBmp.getHeight(), m, true);
// calculate real scale
float rScale = (float) Math
.sqrt((v[Matrix.MSCALE_X] * v[Matrix.MSCALE_X])
+ (v[Matrix.MSKEW_Y] * v[Matrix.MSKEW_Y]));
// Scale viewBmp
Matrix m1 = new Matrix();
m1.postScale(rScale, rScale, width / 2, height / 2);
Bitmap scaledBitmap = Bitmap.createBitmap(bmap, 0, 0, width, height,
m1, true);
// Finally Get cropped Bitmap
Bitmap resultingImage = Bitmap.createBitmap(orgBitmap, (int) left,
(int) top, scaledBitmap.getWidth(), scaledBitmap.getHeight());
return resultingImage;
}
I've been looking for over a day for a solution to this problem but nothing helps, even the answers here. Documentation doesn't explain anything too.
I am simply trying to get a rotation in the direction of another object. The problem is that the bitmap is not rotated around a fixed point, but rather around the bitmaps (0,0).
Here is the code I am having troubles with:
Matrix mtx = new Matrix();
mtx.reset();
mtx.preTranslate(-centerX, -centerY);
mtx.setRotate((float)direction, -centerX, -centerY);
mtx.postTranslate(pivotX, pivotY);
Bitmap rotatedBMP = Bitmap.createBitmap(bitmap, 0, 0, spriteWidth, spriteHeight, mtx, true);
this.bitmap = rotatedBMP;
The weird part is, it doesn't matter how I change the values within pre/postTranslate() and the float arguments in setRotation(). Can someone please help and push me in the right direction? :)
I hope the following sequence of code will help you:
Bitmap targetBitmap = Bitmap.createBitmap(targetWidth, targetHeight, config);
Canvas canvas = new Canvas(targetBitmap);
Matrix matrix = new Matrix();
matrix.setRotate(mRotation,source.getWidth()/2,source.getHeight()/2);
canvas.drawBitmap(source, matrix, new Paint());
If you check the following method from ~frameworks\base\graphics\java\android\graphics\Bitmap.java
public static Bitmap createBitmap(Bitmap source, int x, int y, int width, int height,
Matrix m, boolean filter)
this would explain what it does with rotation and translate.
Edited: optimized code.
public static Bitmap RotateBitmap(Bitmap source, float angle)
{
Matrix matrix = new Matrix();
matrix.postRotate(angle);
return Bitmap.createBitmap(source, 0, 0, source.getWidth(), source.getHeight(), matrix, true);
}
To get Bitmap from resources:
Bitmap source = BitmapFactory.decodeResource(this.getResources(), R.drawable.your_img);
I came back to this problem now that we are finalizing the game and I just thought to post what worked for me.
This is the method for rotating the Matrix:
this.matrix.reset();
this.matrix.setTranslate(this.floatXpos, this.floatYpos);
this.matrix.postRotate((float)this.direction, this.getCenterX(), this.getCenterY());
(this.getCenterX() is basically the bitmaps X position + the bitmaps width / 2)
And the method for Drawing the bitmap (called via a RenderManager Class):
canvas.drawBitmap(this.bitmap, this.matrix, null);
So it is prettey straight forward but I find it abit strange that I couldn't get it to work by setRotate followed by postTranslate. Maybe some knows why this doesn't work? Now all the bitmaps rotate properly but it is not without some minor decrease in bitmap quality :/
Anyways, thanks for your help!
You can also rotate the ImageView using a RotateAnimation:
RotateAnimation rotateAnimation = new RotateAnimation(from, to,
Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF,
0.5f);
rotateAnimation.setInterpolator(new LinearInterpolator());
rotateAnimation.setDuration(ANIMATION_DURATION);
rotateAnimation.setFillAfter(true);
imageView.startAnimation(rotateAnimation);
You can use something like following:
Matrix matrix = new Matrix();
matrix.setRotate(mRotation,source.getWidth()/2,source.getHeight()/2);
RectF rectF = new RectF(0, 0, source.getWidth(), source.getHeight());
matrix.mapRect(rectF);
Bitmap targetBitmap = Bitmap.createBitmap(rectF.width(), rectF.height(), config);
Canvas canvas = new Canvas(targetBitmap);
canvas.drawBitmap(source, matrix, new Paint());
Look at the sample from Google called Lunar Lander, the ship image there is rotated dynamically.
Lunar Lander code sample
I used this configurations and still have the problem of pixelization :
Bitmap bmpOriginal = BitmapFactory.decodeResource(this.getResources(), R.drawable.map_pin);
Bitmap targetBitmap = Bitmap.createBitmap((bmpOriginal.getWidth()),
(bmpOriginal.getHeight()),
Bitmap.Config.ARGB_8888);
Paint p = new Paint();
p.setAntiAlias(true);
Matrix matrix = new Matrix();
matrix.setRotate((float) lock.getDirection(),(float) (bmpOriginal.getWidth()/2),
(float)(bmpOriginal.getHeight()/2));
RectF rectF = new RectF(0, 0, bmpOriginal.getWidth(), bmpOriginal.getHeight());
matrix.mapRect(rectF);
targetBitmap = Bitmap.createBitmap((int)rectF.width(), (int)rectF.height(), Bitmap.Config.ARGB_8888);
Canvas tempCanvas = new Canvas(targetBitmap);
tempCanvas.drawBitmap(bmpOriginal, matrix, p);
matrix.reset();
matrix.setTranslate( anchor.x, anchor.y );
matrix.postRotate((float) rotation , 0,0);
matrix.postTranslate(positionOfAnchor.x, positionOfAnchor.x);
c.drawBitmap(bitmap, matrix, null);
I am trying to rotate a bitmap image 90 degrees to change it from a landscape format to a portrait format. Example:
[a, b, c, d]
[e, f, g, h]
[i, j, k, l]
rotated 90 degree clockwise becomes
[i,e,a]
[j,f,b]
[k,g,c]
[l,h,d]
Using the code below (from an online example) the image is rotated 90 degrees but retains the landscape aspect ratio so you end up with a vertically squashed image. Am I doing something wrong? Is there another method I need to use? I am also willing to rotate the jpeg file that I'm using to create the bitmap if that is easier.
// create a matrix for the manipulation
Matrix matrix = new Matrix();
// resize the bit map
matrix.postScale(scaleWidth, scaleHeight);
// rotate the Bitmap
matrix.postRotate(90);
// recreate the new Bitmap
Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOriginal, 0, 0, widthOriginal, heightOriginal, matrix, true);
This is all you need to rotate the image:
Matrix matrix = new Matrix();
matrix.postRotate(90);
rotated = Bitmap.createBitmap(original, 0, 0,
original.getWidth(), original.getHeight(),
matrix, true);
In your code sample, you included a call to postScale. Could that be the reason your image is being stretched? Perhaps take that one out and do some more testing.
Here's how you would rotate it properly (this insures proper rotation of the image)
public static Bitmap rotate(Bitmap b, int degrees) {
if (degrees != 0 && b != null) {
Matrix m = new Matrix();
m.setRotate(degrees, (float) b.getWidth() / 2, (float) b.getHeight() / 2);
try {
Bitmap b2 = Bitmap.createBitmap(
b, 0, 0, b.getWidth(), b.getHeight(), m, true);
if (b != b2) {
b.recycle();
b = b2;
}
} catch (OutOfMemoryError ex) {
throw ex;
}
}
return b;
}
This code worked great for me:
Matrix matrix = new Matrix();
matrix.setRotate(90, 0, 0);
matrix.postTranslate(original.getHeight(), 0);
rotatedBitmap = Bitmap.createBitmap(newWidth, newHeight, original.getConfig());
Canvas tmpCanvas = new Canvas(rotatedBitmap);
tmpCanvas.drawBitmap(original, matrix, null);
tmpCanvas.setBitmap(null);
check the canvas size where you draw the bitmap, maybe your canvas is still landscape, so only the square part of the rotated bitmap could be seen.
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);