I am trying to make a bounding box over the blue-colored pixels (from Kinect v1 camera, using Processing). Y-axis of bounding box works perfectly but x-axis is very off.
void display() {
PImage img = kinect.getDepthImage();
float maxValue = 0;
float minValue = kinect.width*kinect.height ;
float maxValueX = 0;
float maxValueY = 0;
float minValueX = kinect.width;
float minValueY = kinect.height;
// Being overly cautious here
if (depth == null || img == null) return;
display.loadPixels();
for (int x = 0; x < kinect.width; x++) { //goes through all the window
for (int y = 0; y < kinect.height; y++) {
int offset = x + y * kinect.width;
// Raw depth
int rawDepth = depth[offset];
int pix = x + y * display.width; //why is it y*width
if (rawDepth < threshold) {
// A blue color instead
display.pixels[pix] = color(0, 0, 255); //set correct pixels to blue
if(pix > maxValue){
maxValue = pix;
maxValueX = x;
maxValueY = y;
}
if(pix < minValue){
minValue = pix;
minValueX = x;
minValueY = y;
}
} else {
display.pixels[pix] = img.pixels[offset];
}
}
}
display.updatePixels();
image(display, 0, 0);
rect(minValueX, minValueY, maxValueX-minValueX, maxValueY-minValueY);
}
You have to calculate the minimum and maximum values for each index or coordinate separately. Use the min respectively max function for this:
maxValue = max(maxValue, pix);
minValue = min(minValue, pix);
maxValueX = max(maxValueX, x);
minValueX = min(minValueX, x);
maxValueY = max(maxValueY, y);
minValueY = min(minValueY, y);
or with an ifstatement:
if (pix > maxValue) { maxValue = pix; }
if (pix < minValue) { minValue = pix; }
if (x > maxValueX) { maxValueX = x; }
if (x < minValueX) { minValueX = x; }
if (y > maxValueY) { maxValueY = y; }
if (y < minValueY) { minValueY = y; }
Related
I am currently trying to draw just a section of a BufferedImage that is within the bounds of a Rectangle on the fly. The image gets moved, and thus the size of the image in the rectangle changes.
Visual depiction:
Currently, this is what I have and it works great with a low res image. But if I scale the minimap up, this becomes very inefficient and causes lag
private BufferedImage extractPixels() {
int[] imagePixels = new int[scaledImage.getWidth() * scaledImage.getHeight()];
scaledImage.getRGB(0, 0, scaledImage.getWidth(), scaledImage.getHeight(), imagePixels,
0, scaledImage.getWidth());
int maxX = 0, maxY = 0;
boolean first = false;
for (int y = 0; y < scaledImage.getHeight(); y++) {
for (int x = 0; x < scaledImage.getWidth(); x++) {
int px = (int)(this.x + x);
int py = (int)(this.y + y);
if (viewingArea.contains(px, py)) {
if (x > maxX) maxX = x;
if (y > maxY) maxY = y;
if (!first) {
imageX = x;
imageY = y;
first = true;
}
}
}
}
int xCount = maxX - imageX;
int yCount = maxY - imageY;
if (imageX < 0 || imageX > scaledImage.getWidth() || imageX + xCount > scaledImage.getWidth()) return null;
if (imageY < 0 || imageY > scaledImage.getHeight() || imageY + yCount > scaledImage.getHeight()) return null;
return scaledImage.getSubimage(imageX, imageY, xCount, yCount);
}
In Render loop:
public void Render(PixelRenderer renderer) {
BufferedImage image = extractPixels();
if (image != null) renderer.renderImage(image, x + imageX, y + imageY);
}
Is there a way to do this more efficiently, so that re-scaling has less of an effect on performance?
Fixed by calculating where the image should subimage from, and the size of the subimage dependent on the position of the main image.
private BufferedImage extractPixels() {
double xp = viewingArea.x - this.x;
double yp = viewingArea.y - this.y;
double iw = viewingArea.width;
double ih = viewingArea.height;
int rightBound = scaledImage.getWidth() - viewingArea.width;
int bottomBound = scaledImage.getHeight() - viewingArea.height;
if (xp < 0) {
xp = 0;
iw = viewingArea.width - (this.x - viewingArea.x);
imageX = viewingArea.x + (viewingArea.width - (int)iw);
} else if (xp >= 0 && xp < rightBound) {
xp -= dx;
iw -= dx;
imageX = viewingArea.x;
}
if (xp >= rightBound) {
iw = viewingArea.width - ((int)xp - (scaledImage.getWidth() - viewingArea.width));
imageX = viewingArea.x;
}
if (yp < 0) {
yp = 0;
ih = viewingArea.height - (this.y - viewingArea.y);
imageY = viewingArea.x + (viewingArea.height - (int)ih);
} else if (yp >= 0 && yp < bottomBound) {
yp -= dy;
ih -= dy;
imageY = viewingArea.y;
}
if (yp >= bottomBound) {
ih = viewingArea.height - ((int)yp - (scaledImage.getHeight() - viewingArea.height));
imageY = viewingArea.y;
}
if (iw < 0) iw = Math.abs(iw);
if (ih < 0) ih = Math.abs(ih);
if (xp < 0) xp = Math.abs(xp);
if (yp < 0) yp = Math.abs(yp);
BufferedImage result = new BufferedImage((int)iw, (int)ih, BufferedImage.TYPE_INT_RGB);
try {
result = scaledImage.getSubimage((int)xp, (int)yp, (int)iw, (int)ih);
} catch (Exception e) {
//TODO: Log to game engine something bad has happened
e.printStackTrace();
}
return result;
}
I am trying to make a processing program, but if I use P2D, P3D, or OPENGL mode I get an error:
com.sun.jdi.VMDisconnectedException
at com.sun.tools.jdi.TargetVM.waitForReply(TargetVM.java:285)
at com.sun.tools.jdi.VirtualMachineImpl.waitForTargetReply(VirtualMachineImpl.java:1015)
at com.sun.tools.jdi.PacketStream.waitForReply(PacketStream.java:51)
at com.sun.tools.jdi.JDWP$ObjectReference$InvokeMethod.waitForReply(JDWP.java:4589)
at com.sun.tools.jdi.ObjectReferenceImpl.invokeMethod(ObjectReferenceImpl.java:374)
at processing.mode.java.runner.Runner.findException(Runner.java:701)
at processing.mode.java.runner.Runner.reportException(Runner.java:652)
at processing.mode.java.runner.Runner.exception(Runner.java:595)
at processing.mode.java.runner.EventThread.exceptionEvent(EventThread.java:367)
at processing.mode.java.runner.EventThread.handleEvent(EventThread.java:255)
at processing.mode.java.runner.EventThread.run(EventThread.java:89)
the error message itself varies between P2D and P3D, but they both get a no framebuffer objects available error. I am using processing 2.0b7, please help and let me know if you need more info.
Note: I don't know if this is a separate issue or not, but I am also getting GLSL shader errors to.
Now, here is my code:
Cell[][] Cells = new Cell[50][50];
byte Direction = 1;
byte Times = 1;
int oldwidth = 500;
int oldheight = 500;
void setup() {
size(oldwidth, oldheight, OPENGL);
background(255);
colorMode(HSB,250);
for (int x = 0; x < 50; x++) {
for (int y = 0; y < 50; y++) {
Cells[x][y] = new Cell(x * 5, y * 5, 255, x * (width / 50), y * (height / 50), width / 50, height / 50);
}
}
}
void draw() {
for (int x = 0; x < 50; x++) {
for (int y = 0; y < 50; y++) {
if (width == oldwidth) Cells[x][y].Width = width / 50;
if (height == oldheight) Cells[x][y].Height = height / 50;
if (Direction == 1){
Cells[x][y].Hue += 5;
if (Cells[x][y].Hue > 250) Cells[x][y].Hue -= 250;
}
if (Direction == 2){
Cells[x][y].Saturation -= 5;
if (Cells[x][y].Saturation < 0) Cells[x][y].Saturation += 500;
}
if (Direction == 3){
Cells[x][y].Hue -= 5;
if (Cells[x][y].Hue < 0) Cells[x][y].Hue += 250;
}
if (Direction == 4){
Cells[x][y].Saturation += 5;
if (Cells[x][y].Saturation > 500) Cells[x][y].Saturation -= 500;
}
Cells[x][y].Draw();
}
}
if (Times == 50){
Times = 1;
if (Direction == 4) Direction = 1; else Direction += 1;
} else Times += 1;
delay(10);
}
class Cell {
int X;
int Y;
int Width;
int Height;
float Hue;
float Saturation;
float Brightness;
Cell(color parC, int parX, int parY, int parWidth, int parHeight) {
Hue = hue(parC);
Saturation = saturation(parC);
Brightness = brightness(parC);
X = parX;
Y = parY;
Width = parWidth;
Height = parHeight;
}
Cell(float parHue, float parSaturation, float parBrightness, int parX, int parY, int parWidth, int parHeight) {
Hue = parHue;
Saturation = parSaturation;
Brightness = parBrightness;
X = parX;
Y = parY;
Width = parWidth;
Height = parHeight;
}
void Draw() {
if (Saturation > 250) if (Saturation > 500) stroke(color(Hue,0,Brightness)); else stroke(color(Hue,Saturation - (Saturation - 250) * 2,Brightness)); else stroke(color(Hue,Saturation,Brightness));
if (Saturation > 250) if (Saturation > 500) fill(color(Hue,0,Brightness)); else fill(color(Hue,Saturation - (Saturation - 250) * 2,Brightness)); else fill(color(Hue,Saturation,Brightness));
rect(X, Y, Width, Height);
}
}
I just realized that it is just that my graphics card does not support OPENGL 2.0
I have a set of bitmaps. They are all transparent to some extent, and I don't know in advance which parts are transparent. I would like to create a new bitmap out of the original bitmap that excludes the transparent parts, but in a square. I think this image explains it:
I know how to create a bitmap out of a existing bitmap, but I don't know how to find out which part is transparent and how to use that to achieve my goal.
This is how I plan on doing this:
public Bitmap cutImage(Bitmap image) {
Bitmap newBitmap = null;
int width = image.getWidth();
int height = image.getHeight();
newBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(newBitmap);
//This is where I need to find out correct values of r1 and r1.
Rect r1 = new Rect(?, ?, ?, ?);
Rect r2 = new Rect(?, ?, ?, ?);
canvas.drawBitmap(image, r1, r2, null);
return newBitmap;
}
Does anyone know how to achieve this?
EDIT:
I got it work using the following algorithm to find left, right, top and bottom values:
private int x1;
private int x2;
private int y1;
private int y2;
private void findRectValues(Bitmap image)
{
for(int x = 0; x < image.getWidth(); x++)
{
for(int y = 0; y < image.getHeight(); y++)
{
if(image.getPixel(x, y) != Color.TRANSPARENT)
{
System.out.println("X1 is: " + x);
x1 = x;
break;
}
}
if(x1 != 0)
break;
}
for(int x = image.getWidth()-1; x > 0; x--)
{
for(int y = 0; y < image.getHeight(); y++)
{
if(image.getPixel(x, y) != Color.TRANSPARENT)
{
System.out.println("X2 is: " + x);
x2 = x;
break;
}
}
if(x2 != 0)
break;
}
for(int y = 0; y < image.getHeight(); y++)
{
for(int x = 0; x < image.getWidth(); x++)
{
if(image.getPixel(x, y) != Color.TRANSPARENT)
{
System.out.println("Y1 is: " + y);
y1 = y;
break;
}
}
if(y1 != 0)
break;
}
for(int y = image.getHeight()-1; y > 0; y--)
{
for(int x = 0; x < image.getWidth(); x++)
{
if(image.getPixel(x, y) != Color.TRANSPARENT)
{
System.out.println("Y2 is: " + y);
y2 = y;
break;
}
}
if(y2 != 0)
break;
}
}
i think this is a bit more efficient and it works great for me
public Bitmap cropBitmapToBoundingBox(Bitmap picToCrop, int unusedSpaceColor) {
int[] pixels = new int[picToCrop.getHeight() * picToCrop.getWidth()];
int marginTop = 0, marginBottom = 0, marginLeft = 0, marginRight = 0, i;
picToCrop.getPixels(pixels, 0, picToCrop.getWidth(), 0, 0,
picToCrop.getWidth(), picToCrop.getHeight());
for (i = 0; i < pixels.length; i++) {
if (pixels[i] != unusedSpaceColor) {
marginTop = i / picToCrop.getWidth();
break;
}
}
outerLoop1: for (i = 0; i < picToCrop.getWidth(); i++) {
for (int j = i; j < pixels.length; j += picToCrop.getWidth()) {
if (pixels[j] != unusedSpaceColor) {
marginLeft = j % picToCrop.getWidth();
break outerLoop1;
}
}
}
for (i = pixels.length - 1; i >= 0; i--) {
if (pixels[i] != unusedSpaceColor) {
marginBottom = (pixels.length - i) / picToCrop.getWidth();
break;
}
}
outerLoop2: for (i = pixels.length - 1; i >= 0; i--) {
for (int j = i; j >= 0; j -= picToCrop.getWidth()) {
if (pixels[j] != unusedSpaceColor) {
marginRight = picToCrop.getWidth()
- (j % picToCrop.getWidth());
break outerLoop2;
}
}
}
return Bitmap.createBitmap(picToCrop, marginLeft, marginTop,
picToCrop.getWidth() - marginLeft - marginRight,
picToCrop.getHeight() - marginTop - marginBottom);
}
If all the images you want to crop are more or less in the center of the original canvas, I guess you could so something like this:
Start from each border working your way inwards the image searching for non-transparent pixels
Once you've found the top-left pixel and the right-bottom, you'll have your desired target.
Copy the image as you please
Now, the question remains is what you consider a transparent pixel. Does alpha trasparency counts? if so, how much alpha until you decide it's transparent enough to be cut from the image?
To find the non-transparent area of your bitmap, iterate across the bitmap in x and y and find the min and max of the non-transparent region. Then crop the bitmap to those co-ordinates.
Bitmap CropBitmapTransparency(Bitmap sourceBitmap)
{
int minX = sourceBitmap.getWidth();
int minY = sourceBitmap.getHeight();
int maxX = -1;
int maxY = -1;
for(int y = 0; y < sourceBitmap.getHeight(); y++)
{
for(int x = 0; x < sourceBitmap.getWidth(); x++)
{
int alpha = (sourceBitmap.getPixel(x, y) >> 24) & 255;
if(alpha > 0) // pixel is not 100% transparent
{
if(x < minX)
minX = x;
if(x > maxX)
maxX = x;
if(y < minY)
minY = y;
if(y > maxY)
maxY = y;
}
}
}
if((maxX < minX) || (maxY < minY))
return null; // Bitmap is entirely transparent
// crop bitmap to non-transparent area and return:
return Bitmap.createBitmap(sourceBitmap, minX, minY, (maxX - minX) + 1, (maxY - minY) + 1);
}
I'm trying to make a program that simulates the physics of fluids in Processing. In the IDE there's an included example:
/**
* Fluid
* by Glen Murphy.
*
* Click and drag the mouse to move the simulated fluid.
* Adjust the "res" variable below to change resolution.
* Code has not been optimised, and will run fairly slowly.
*/
int res = 2;
int penSize = 30;
int lwidth;
int lheight;
int pnum = 30000;
vsquare[][] v;
vbuffer[][] vbuf;
particle[] p = new particle[pnum];
int pcount = 0;
int mouseXvel = 0;
int mouseYvel = 0;
void setup()
{
size(200, 200);
noStroke();
frameRate(30);
lwidth = width/res;
lheight = height/res;
v = new vsquare[lwidth+1][lheight+1];
vbuf = new vbuffer[lwidth+1][lheight+1];
for (int i = 0; i < pnum; i++) {
p[i] = new particle(random(res,width-res),random(res,height-res));
}
for (int i = 0; i <= lwidth; i++) {
for (int u = 0; u <= lheight; u++) {
v[i][u] = new vsquare(i*res,u*res);
vbuf[i][u] = new vbuffer(i*res,u*res);
}
}
}
void draw()
{
background(#666666);
int axvel = mouseX-pmouseX;
int ayvel = mouseY-pmouseY;
mouseXvel = (axvel != mouseXvel) ? axvel : 0;
mouseYvel = (ayvel != mouseYvel) ? ayvel : 0;
for (int i = 0; i < lwidth; i++) {
for (int u = 0; u < lheight; u++) {
vbuf[i][u].updatebuf(i,u);
v[i][u].col = 32;
}
}
for (int i = 0; i < pnum-1; i++) {
p[i].updatepos();
}
for (int i = 0; i < lwidth; i++) {
for (int u = 0; u < lheight; u++) {
v[i][u].addbuffer(i, u);
v[i][u].updatevels(mouseXvel, mouseYvel);
v[i][u].display(i, u);
}
}
}
class particle {
float x;
float y;
float xvel;
float yvel;
int pos;
particle(float xIn, float yIn) {
x = xIn;
y = yIn;
}
void updatepos() {
float col1;
if (x > 0 && x < width && y > 0 && y < height) {
int vi = (int)(x/res);
int vu = (int)(y/res);
vsquare o = v[vi][vu];
float ax = (x%res)/res;
float ay = (y%res)/res;
xvel += (1-ax)*v[vi][vu].xvel*0.05;
yvel += (1-ay)*v[vi][vu].yvel*0.05;
xvel += ax*v[vi+1][vu].xvel*0.05;
yvel += ax*v[vi+1][vu].yvel*0.05;
xvel += ay*v[vi][vu+1].xvel*0.05;
yvel += ay*v[vi][vu+1].yvel*0.05;
o.col += 4;
x += xvel;
y += yvel;
}
else {
x = random(0,width);
y = random(0,height);
xvel = 0;
yvel = 0;
}
xvel *= 0.5;
yvel *= 0.5;
}
}
class vbuffer {
int x;
int y;
float xvel;
float yvel;
float pressurex = 0;
float pressurey = 0;
float pressure = 0;
vbuffer(int xIn,int yIn) {
x = xIn;
y = yIn;
pressurex = 0;
pressurey = 0;
}
void updatebuf(int i, int u) {
if (i>0 && i<lwidth && u>0 && u<lheight) {
pressurex = (v[i-1][u-1].xvel*0.5 + v[i-1][u].xvel + v[i-1][u+1].xvel*0.5 - v[i+1][u-1].xvel*0.5 - v[i+1][u].xvel - v[i+1][u+1].xvel*0.5);
pressurey = (v[i-1][u-1].yvel*0.5 + v[i][u-1].yvel + v[i+1][u-1].yvel*0.5 - v[i-1][u+1].yvel*0.5 - v[i][u+1].yvel - v[i+1][u+1].yvel*0.5);
pressure = (pressurex + pressurey)*0.25;
}
}
}
class vsquare {
int x;
int y;
float xvel;
float yvel;
float col;
vsquare(int xIn,int yIn) {
x = xIn;
y = yIn;
}
void addbuffer(int i, int u) {
if (i>0 && i<lwidth && u>0 && u<lheight) {
xvel += (vbuf[i-1][u-1].pressure*0.5
+vbuf[i-1][u].pressure
+vbuf[i-1][u+1].pressure*0.5
-vbuf[i+1][u-1].pressure*0.5
-vbuf[i+1][u].pressure
-vbuf[i+1][u+1].pressure*0.5
)*0.25;
yvel += (vbuf[i-1][u-1].pressure*0.5
+vbuf[i][u-1].pressure
+vbuf[i+1][u-1].pressure*0.5
-vbuf[i-1][u+1].pressure*0.5
-vbuf[i][u+1].pressure
-vbuf[i+1][u+1].pressure*0.5
)*0.25;
}
}
void updatevels(int mvelX, int mvelY) {
if (mousePressed) {
float adj = x - mouseX;
float opp = y - mouseY;
float dist = sqrt(opp*opp + adj*adj);
if (dist < penSize) {
if (dist < 4) dist = penSize;
float mod = penSize/dist;
xvel += mvelX*mod;
yvel += mvelY*mod;
}
}
xvel *= 0.99;
yvel *= 0.99;
}
void display(int i, int u) {
float tcol = 0;
if (col > 255) col = 255;
if (i>0 && i<lwidth-1 && u>0 && u<lheight-1) {
tcol = (+ v[i][u+1].col
+ v[i+1][u].col
+ v[i+1][u+1].col*0.5
)*0.4;
tcol = (int)(tcol+col*0.5);
}
else {
tcol = (int)col;
}
fill(tcol, tcol, tcol);
rect(x,y,res,res);
}
}
It's not really commented and I'm somewhat new to programming, so I have no idea where to start as far as understanding it. Is there any good reading on fluid physics? I'm more interesting in the visual effect than the accuracy of the simulation.
A good starting point could be the paper Stable Fluids, it will show you the math behind the fluid simulation, and in the third chapter it describe the implementation of a fluid solver. There is also an open source implementation available in sourceforge (you will need to checkout the source with cvs).
I have a sprite sheet which has each image centered in a 32x32 cell. The actual images are not 32x32, but slightly smaller. What I'd like to do is take a cell and crop the transparent pixels so the image is as small as it can be.
How would I do that in Java (JDK 6)?
Here is an example of how I'm currently breaking up the tile sheet into cells:
BufferedImage tilesheet = ImageIO.read(getClass().getResourceAsStream("/sheet.png");
for (int i = 0; i < 15; i++) {
Image img = tilesheet.getSubimage(i * 32, 0, 32, 32);
// crop here..
}
My current idea was to test each pixel from the center working my way out to see if it is transparent, but I was wondering if there would be a faster/cleaner way of doing this.
There's a trivial solution – to scan every pixel. The algorithm bellow has a constant performance of O(w•h).
private static BufferedImage trimImage(BufferedImage image) {
int width = image.getWidth();
int height = image.getHeight();
int top = height / 2;
int bottom = top;
int left = width / 2 ;
int right = left;
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
if (image.getRGB(x, y) != 0){
top = Math.min(top, y);
bottom = Math.max(bottom, y);
left = Math.min(left, x);
right = Math.max(right, x);
}
}
}
return image.getSubimage(left, top, right - left + 1, bottom - top + 1);
}
But this is much more effective:
private static BufferedImage trimImage(BufferedImage image) {
WritableRaster raster = image.getAlphaRaster();
int width = raster.getWidth();
int height = raster.getHeight();
int left = 0;
int top = 0;
int right = width - 1;
int bottom = height - 1;
int minRight = width - 1;
int minBottom = height - 1;
top:
for (;top <= bottom; top++){
for (int x = 0; x < width; x++){
if (raster.getSample(x, top, 0) != 0){
minRight = x;
minBottom = top;
break top;
}
}
}
left:
for (;left < minRight; left++){
for (int y = height - 1; y > top; y--){
if (raster.getSample(left, y, 0) != 0){
minBottom = y;
break left;
}
}
}
bottom:
for (;bottom > minBottom; bottom--){
for (int x = width - 1; x >= left; x--){
if (raster.getSample(x, bottom, 0) != 0){
minRight = x;
break bottom;
}
}
}
right:
for (;right > minRight; right--){
for (int y = bottom; y >= top; y--){
if (raster.getSample(right, y, 0) != 0){
break right;
}
}
}
return image.getSubimage(left, top, right - left + 1, bottom - top + 1);
}
This algorithm follows the idea from pepan's answer (see above) and is 2 to 4 times more effective. The difference is: it never scans any pixel twice and tries to contract search range on each stage.
The worst case of the method's performance is O(w•h–a•b)
This code works for me. The algorithm is simple, it iterates from left/top/right/bottom of the picture and finds the very first pixel in the column/row which is not transparent. It then remembers the new corner of the trimmed picture and finally it returns the sub image of the original image.
There are things which could be improved.
The algorithm expects, there is the alpha byte in the data. It will fail on an index out of array exception if there is not.
The algorithm expects, there is at least one non-transparent pixel in the picture. It will fail if the picture is completely transparent.
private static BufferedImage trimImage(BufferedImage img) {
final byte[] pixels = ((DataBufferByte) img.getRaster().getDataBuffer()).getData();
int width = img.getWidth();
int height = img.getHeight();
int x0, y0, x1, y1; // the new corners of the trimmed image
int i, j; // i - horizontal iterator; j - vertical iterator
leftLoop:
for (i = 0; i < width; i++) {
for (j = 0; j < height; j++) {
if (pixels[(j*width+i)*4] != 0) { // alpha is the very first byte and then every fourth one
break leftLoop;
}
}
}
x0 = i;
topLoop:
for (j = 0; j < height; j++) {
for (i = 0; i < width; i++) {
if (pixels[(j*width+i)*4] != 0) {
break topLoop;
}
}
}
y0 = j;
rightLoop:
for (i = width-1; i >= 0; i--) {
for (j = 0; j < height; j++) {
if (pixels[(j*width+i)*4] != 0) {
break rightLoop;
}
}
}
x1 = i+1;
bottomLoop:
for (j = height-1; j >= 0; j--) {
for (i = 0; i < width; i++) {
if (pixels[(j*width+i)*4] != 0) {
break bottomLoop;
}
}
}
y1 = j+1;
return img.getSubimage(x0, y0, x1-x0, y1-y0);
}
I think this is exactly what you should do, loop through the array of pixels, check for alpha and then discard. Although when you for example would have a star shape it will not resize the image to be smaller be aware of this.
A simple fix for code above. I used the median for RGB and fixed the min() function of x and y:
private static BufferedImage trim(BufferedImage img) {
int width = img.getWidth();
int height = img.getHeight();
int top = height / 2;
int bottom = top;
int left = width / 2 ;
int right = left;
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
if (isFg(img.getRGB(x, y))){
top = Math.min(top, y);
bottom = Math.max(bottom, y);
left = Math.min(left, x);
right = Math.max(right, x);
}
}
}
return img.getSubimage(left, top, right - left, bottom - top);
}
private static boolean isFg(int v) {
Color c = new Color(v);
return(isColor((c.getRed() + c.getGreen() + c.getBlue())/2));
}
private static boolean isColor(int c) {
return c > 0 && c < 255;
}
[Hi I tried the following. In the images file idle1.png is the image with a big transparent box while testing.png is the same image with minimum bounding box
'BufferedImage tempImg = (ImageIO.read(new File(fileNPath)));
WritableRaster tempRaster = tempImg.getAlphaRaster();
int x1 = getX1(tempRaster);
int y1 = getY1(tempRaster);
int x2 = getX2(tempRaster);
int y2 = getY2(tempRaster);
System.out.println("x1:"+x1+" y1:"+y1+" x2:"+x2+" y2:"+y2);
BufferedImage temp = tempImg.getSubimage(x1, y1, x2 - x1, y2 - y1);
//for idle1.png
String filePath = fileChooser.getCurrentDirectory() + "\\"+"testing.png";
System.out.println("filePath:"+filePath);
ImageIO.write(temp,"png",new File(filePath));
where the get functions are
public int getY1(WritableRaster raster) {
//top of character
for (int y = 0; y < raster.getHeight(); y++) {
for (int x = 0; x < raster.getWidth(); x++) {
if (raster.getSample(x, y,0) != 0) {
if(y>0) {
return y - 1;
}else{
return y;
}
}
}
}
return 0;
}
public int getY2(WritableRaster raster) {
//ground plane of character
for (int y = raster.getHeight()-1; y > 0; y--) {
for (int x = 0; x < raster.getWidth(); x++) {
if (raster.getSample(x, y,0) != 0) {
return y + 1;
}
}
}
return 0;
}
public int getX1(WritableRaster raster) {
//left side of character
for (int x = 0; x < raster.getWidth(); x++) {
for (int y = 0; y < raster.getHeight(); y++) {
if (raster.getSample(x, y,0) != 0) {
if(x > 0){
return x - 1;
}else{
return x;
}
}
}
}
return 0;
}
public int getX2(WritableRaster raster) {
//right side of character
for (int x = raster.getWidth()-1; x > 0; x--) {
for (int y = 0; y < raster.getHeight(); y++) {
if (raster.getSample(x, y,0) != 0) {
return x + 1;
}
}
}
return 0;
}'[Look at Idle1.png and the minimum bounding box idle = testing.png][1]
Thank you for your help regards Michael.Look at Idle1.png and the minimum bounding box idle = testing.png]images here
If your sheet already has transparent pixels, the BufferedImage returned by getSubimage() will, too. The default Graphics2D composite rule is AlphaComposite.SRC_OVER, which should suffice for drawImage().
If the sub-images have a distinct background color, use a LookupOp with a four-component LookupTable that sets the alpha component to zero for colors that match the background.
I'd traverse the pixel raster only as a last resort.
Addendum: Extra transparent pixels may interfere with collision detection, etc. Cropping them will require working with a WritableRaster directly. Rather than working from the center out, I'd start with the borders, using a pair of getPixels()/setPixels() methods that can modify a row or column at a time. If a whole row or column has zero alpha, mark it for elimination when you later get a sub-image.