how to rotate a rectangle in canvas?
for example.
Rectangle Box = new Rectangle(100,100,100,100);
and i want to rotate this by (for example)38 degres.
Someone know how i can do it?
Related
I am trying to fill in a specific rectangle when a user clicks it. A picture of the grid is below:
Grid Layout
So when a user clicks on one of the rectangles it should be filled in with the selected color. I have already done the color part and I am drawing and then filling rectangles. However, my rectangles do not stay within the clicked rectangle because I am not calculating where the grid rectangle is.
Here is how I am getting the starting position to draw a rectangle:
positionX = event.getX();
positionY = event.getY();
width = getSize().width; // This is wrong
height = getSize().height; // This is wrong
I am then adding the rectangle to an Array with parameters positionX, positionY, width, height, color and calling repaint().
My long winded question is how I should go about knowing which rectangle I am in and coloring that one specifically? I believe I need to base the width and height off of where the mouse is pressed, but since the user can press anywhere in a rectangle, I am unclear on how to do that.
I have detected a area (rectangle) in my image with openCv and i have stored the 4 points of rectangle with their coordinates.
I would to crop the original image in this area.
I have:
Mat image_original;
Point p1,p2,p3,p4;
Mat image_output;
How i do this?
Thanks!
Mat image_original;
Point p1,p2,p3,p4;
Rect rectCrop = new Rect(p1.x, p1.y , (p4.x-p1.x+1), (p4.y-p1.y+1));
Mat image_output= image_original.submat(rectCrop);
This is the code for croping image as per your requirement.I assumed that Point p1 is the top-left corner of the crop rectangle and Point p4 is the bottom-right corner of the crop rectangle as you have not mentioned anything about their positions.
I've got a problem to draw a sprite to my project.
I have a map (960x900) divided into tiles (64x64).
As you can see in the picture, when i click on the bottom left corner of the purple square, the position is (0;0), and when I click on the top right corner of purple square, the position is (36;47)
The problem is that the picture of the purple square has a size of 32x32, and when I draw this picture with libgdx on the screen, the size doesn't match.
Another example: the square with black border has a size of 64x64. So if I draw the purple square in front of the black, the purple should be the half (in height and in width) of the black, no?
Does anyone know why libgdx resizes the purple square?
Sprite sprite = new Sprite(new Texture("assets/purpleSquare.png"));
i draw it in a method
public void render(SpriteBatch batch) {
batch.draw(sprite, 0, 0);
}
I don't know why the picture is resized by libgdx.. I have also tried to do
batch.draw(sprite, 0, 0, width, heigth);
To precise the sprite's size but it doesn't work too..
The size on screen bears no direct relation to the size of the original image. When you draw a sprite you provide the SpriteBatch with a position, width, and height in world coordinates. The sprite will be stretched to fit these world coordinates, regardless of the original image size.
When you click the screen, you are clicking in screen coordinates. The relation between screen and world coordinates is determined by the projection matrix that you use with the SpriteBatch. The projection matrix is typically controlled with a Camera or Viewport object, which you can use to convert between the two coordinate systems using the project and unproject methods.
I'm happy to see that after many hours i found a solution, even if i know which is not correct.
I would like some help to understand the problem's origin.
With this parts of code :
public void update(float delta) {
batch.begin();
drawBackground(); // Draw the background
drawButton(); // Draw the play/pause button
batch.end();
drawMap(); // draw a tmx map made with tiled
batch.begin();
if(!world.isInitial()) {
renderMonster(); // method which draw the monster
}
renderTower(); // method which draw the tower's level
batch.end();
}
I don't understand why i have to do "batch.begin()" and "batch.end()" twice.
I dont' understant why with this code, the purple square is resized.
With this code :
public void update(float delta) {
batch.begin();
drawBackground();
drawButton();
batch.end();
drawMap();
------->sb = new SpriteBatch();
sb.begin();
if(!world.isInitial()) {
renderMonster();
}
renderTower();
sb.end();
}
this line that i add fix the bug with the purple square. If i work with two SpriteBatch (because with one, if i reinitialize SpriteBatch in update method, my pause/play button diseapper) and i initialise the second (SpriteBatch sb) in the update method.
It is correct to initialise a SpriteBatch every time i'm passing on the update method ? There's no method with a SpriteBatch to avoid this problem ?
I'm trying to draw an image within a certain area. Right now I have code that fills an area with a RadialGradientPaint.
Area lightArea = ...
// fill the polygon with the gradient paint
g.setPaint(light.paint);
g.fill(lightArea);
I would like to draw a BufferedImage in that area instead of drawing a RadialGradientPaint. Is there a way I can do that?
You could use BufferdImage#getSubimage
Rectangle bounds = area.getBounds();
BufferedImage img = master.getSubImage(0, 0, Math.min(bounds.width, master.getWidth()), Math.min(bounds.height, master.getHeight());
This assumes that the area is rectangular. If it's not, you cold create a mask image, based on the shape of the Area and use it to generate masked image (cookie cutting the image out of the shape)
As demonstrated here. The benefit of which is it allows for antialiasing
Use Graphics.setClip:
g.setClip(lightArea);
g.drawImage(yourImage, x, y, null);
See http://docs.oracle.com/javase/tutorial/2d/advanced/clipping.html for more details.
Ok when a user draws a Rectangle on top of an image, I want to find all the rotated Rectangles ahead of time for all image rotation angles (90,180,270,360).
According to Java API I can just keep calling the Graphics2D rotate() method. I can then use this Graphics2D transformer to get the rotated Rectangle.
This works for the very first rotation(1.5708) call. I get the correct Rectangle Point. All other calls after that return the wrong Rectangle Point after using Transformer.
I think my problem is the Graphics2D translate(x,y). I don't understand how to use it.
Anyone knows how to fix my code so that it will return the correct Rectangle after every rotation?
Thank you.
public void rotateRectangles(BufferedImage bim,int width,int height,Rectangle rect){
BufferedImage bim = new BufferedImage(height, width,BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = (Graphics2D) (bufferedImage.createGraphics());
g2d.translate(bufferedImage.getHeight(),0);
//Get Rectangle for 90 degree image rotation. This always good.
g2d.rotate(1.5708);
Shape shape = g2d.getTransform().createTransformedShape(rect);
Rectangle rotatedRect = shape.getBounds();
System.out.println("rotated rectangle at 90 degrees. Point x="+rotatedRect.x+" y="+rotatedRect.y);
//Get Rectangle for 180 degree image rotation. Getting wrong rotatedRect.
g2d.rotate(1.5708);
shape = g2d.getTransform().createTransformedShape(rect);
rotatedRect = shape.getBounds();
System.out.println("rotated rectangle at 180 degrees. Point x="+rotatedRect.x+" y="+rotatedRect.y);
//Get Rectangle for 270 degree image rotation. Getting wrong rotatedRect.
g2d.rotate(1.5708);
shape = g2d.getTransform().createTransformedShape(rect);
rotatedRect = shape.getBounds();
System.out.println("rotated rectangle at 270 degrees. Point x="+rotatedRect.x+" y="+rotatedRect.y);
//Get Rectangle for 360 degree image rotation.Getting wrong rotatedRect.
g2d.rotate(1.5708);
shape = g2d.getTransform().createTransformedShape(rect);
rotatedRect = shape.getBounds();
System.out.println("rotated rectangle at 360 degrees. Point x="+rotatedRect.x+" y="+rotatedRect.y);
}
Thank you.
Instead of rotating the graphics context's affine transform via g2d.rotate(), consider using createTransformedShape() as suggested in this example.
Addendum: Note in particular that the baseline of the example Polygon is initially centered on the origin. As a result, the initial transformation is rotation around the origin. In your case, you can use the rotate() method that includes an anchor point, which would be the center of your rectangle.