I want to copy any area in Canvas with x and y coordinates and then paste it to any Image.
In example:
Image image = Image.createImage(30, 20);
image.drawImage(canvas);
It is not possible to copy data from Canvas nor GameCanvas.
To achieve what you want, you have to use doublebuffering. Meaning, you have to use an Image bufferImg as your buffer to draw on, and then draw that bufferImg onto your Canvas.
That way, you can copy from the Image onto another Image like this:
bufferImg.getRGB(int[] rgbData, int offset, int scanlength, int x, int y, int width, int height);
and then
g.drawRGB(int[] rgbData, int offset, int scanlength, int x, int y, int width, int height, boolean processAlpha);
where g is the Graphics object of the 2nd Image you want to draw onto.
Using a doublebuffer like this will slow things down a bit on some devices of course, but you can't do it any other way if you want to be able to "extract" portions of the screen.
Related
I am trying to do some basic drawing with skia. Since I'm working on grayscale images I want to use the corresponding color type. The minimal Example I want to use is:
int main(int argc, char * const argv[])
{
int width = 1000;
int heigth = 1000;
float linewidth = 10.0f;
SkImageInfo info = SkImageInfo::Make(
width,
heigth,
SkColorType::kAlpha_8_SkColorType,
SkAlphaType::kPremul_SkAlphaType
);
SkBitmap img;
img.allocPixels(info);
SkCanvas canvas(img);
canvas.drawColor(SK_ColorBLACK);
SkPaint paint;
paint.setColor(SK_ColorWHITE);
paint.setAlpha(255);
paint.setAntiAlias(false);
paint.setStrokeWidth(linewidth);
paint.setStyle(SkPaint::kStroke_Style);
canvas.drawCircle(500.0f, 500.0f, 100.0f, paint);
bool success = SkImageEncoder::EncodeFile("B:\\img.png", img,
SkImageEncoder::kPNG_Type, 100);
return 0;
}
But the saved image does not contain the circle that was drawn. If I replace kAlpha_8_SkColorType with kN32_SkColorType I get the expected result. How can I draw the circle onto a 8 bit grayscale image? I'm working with Visual Studio 2013 on a 64bit Windows machine.
kN32_SkColorType type result
kAlpha_8_SkColorType result
You should use kGray_8_SkColorType than kAlpha_8_SkColorType.
The kAlpha_8_SkColorType used for bitmap mask.
I want to have a fullscreen mode that keeps the aspect ratio by adding black bars on either side. I tried just creating a display mode, but I can't make it fullscreen unless it's a pre-approved resolution, and when I use a bigger diaplay than the native resolution the pixels become messed up, and lines appeared between all of the tiles in the game for some reason.
I think I need to use FBOs to render the scenario to a texture instead of the window, and then just use a fullscreen approved resolution and render the texture properly stretched out in the center of the screen, but I just don't understand how to render to a texture in order to do that, or how to stretch an image. Could someone please help me?
EDIT
I got fullscreen working, but it makes everything all broken looking There are random lines on the edges of anything that's written to the window. There are no glitchy lines when it's in native resolution though. Here's my code:
Display.setTitle("Mega Man");
try{
Display.setDisplayMode(Display.getDesktopDisplayMode());
Display.create();
}catch(LWJGLException e){
e.printStackTrace();
}
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0,WIDTH,HEIGHT,0,1,-1);
glMatrixMode(GL_MODELVIEW);
glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glHint(GL_LINE_SMOOTH_HINT, GL_NICEST);
try{Display.setFullscreen(true);}catch(Exception e){}
int sh=Display.getHeight();
int sw=WIDTH*sh/HEIGHT;
GL11.glViewport(Display.getWidth()/2-sw/2, 0, sw, sh);
Screenshot of the glitchy fullscreen here: http://sta.sh/021fohgnmxwa
EDIT
Here is the texture rendering code that I use to draw everything:
public static void DrawQuadTex(Texture tex, int x, int y, float width, float height, float texWidth, float texHeight, float subx, float suby, float subd, String mirror){
if (tex==null){return;}
if (mirror==null){mirror = "";}
//subx, suby, and subd are to grab sprites from a sprite sheet. subd is the measure of both the width and length of the sprite, as only images with dimensions that are the same and are powers of 2 are properly displayed.
int xinner = 0;
int xouter = (int) width;
int yinner = 0;
int youter = (int) height;
if (mirror.indexOf("h")>-1){
xinner = xouter;
xouter = 0;
}
if (mirror.indexOf("v")>-1){
yinner = youter;
youter = 0;
}
tex.bind();
glTranslatef(x,y,0);
glBegin(GL_QUADS);
glTexCoord2f(subx/texWidth,suby/texHeight);
glVertex2f(xinner,yinner);
glTexCoord2f((subx+subd)/texWidth,suby/texHeight);
glVertex2f(xouter,yinner);
glTexCoord2f((subx+subd)/texWidth,(suby+subd)/texHeight);
glVertex2f(xouter,youter);
glTexCoord2f(subx/texWidth,(suby+subd)/texHeight);
glVertex2f(xinner,youter);
glEnd();
glLoadIdentity();
}
Just to keep it clean I give you a real answer and not just a comment.
The aspect ratio problem can be solved with help of glViewport. Using this method you can decide which area of the surface that will be rendered to. The default viewport will cover the whole surface.
Since the second problem with the corrupt rendering (also described here https://stackoverflow.com/questions/28846531/sprite-game-in-full-screen-aliasing-issue) appeared after changing viewport I will give my thought about it in this answer as well.
Without knowing exactly how the rendering code for the tile background looks. I would guess that the problem is due to any differences in the resolution between the glViewport and glOrtho calls.
Example: If the glOrtho resolution is half the viewport resolution then each openGL unit is actually 2 pixels. If you then renders a tile between x=0 and x=9 and then the next one between x=10 and x=19 you will get an empty space between them.
To solve this you can change the resolution so that they are the same. Or you can render the tile to overlap, first one x=0 to x=10 second one x=10 to x=20 and so on.
Without seeing the tile rendering code I can't verify it this is the problem though.
I use the following fragment shader, which uses the fog effect, to draw my scene:
precision mediump float;
uniform int EnableFog;
uniform float FogMinDist;
uniform float FogMaxDist;
varying lowp vec4 DestinationColor;
varying float EyeToVertexDist;
float computeFogFactor()
{
float fogFactor = 1.0;
if (EnableFog != 0)
{
//Use a bit lower vlaue of FogMaxDist to get a better fog effect - it will make the far end disappear quicker.
float fogMaxDistABitCloser = FogMaxDist * 0.98;
fogFactor = (fogMaxDistABitCloser - EyeToVertexDist) / (fogMaxDistABitCloser - FogMinDist);
fogFactor = clamp(fogFactor, 0.0, 1.0);
}
return fogFactor;
}
void main(void)
{
float fogFactor = computeFogFactor();
gl_FragColor = DestinationColor * fogFactor;
}
And i enable alpha blending:
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
The result is the following scene:
My problem is with the places in which the lines overlap - the result is that the color seems darker than the color of both lines:
How i can fix it?
As already described in the comment you are blending the newly drawn line with the background which may already contain colours from another object at certain pixels, in your case where lines overlap. To solve this you will either have to draw your lines without overlapping or make your drawing independent from the current buffer state.
In your specific case you may pass the background colour to your fragment shader via some uniform or even a texture and then do your blending manually in the fragment shader.
In general you might want to draw the grid to some frame buffer object (FBO) with attached texture and then draw the whole texture in a single draw call using your fog shader and blending. The drawing to FBO should then be with disabled blending.
There are other ways such as drawing the grid to a stencil buffer first and then redraw a full-screen rect applying a colour with your shader and blending.
Fl::h() excludes the height of the task bar at the bottom.
I have an Fl_Double_Window inside an FL_Window. After I make the outer window (Fl_Window) full screen using fullscreen() method, I want to make the height of the Fl_Double_Window equal to the height of the screen. If I use innerWindow->size(Fl::w(), Fl::h()); it does not extend its height all the way to the bottom of the screen.
I believe Fl::w() and Fl::h() will give you width and height of the working area. After examining the list of screen functions I believe your best option is to get the number of screens using the static int Fl::screen_count () and then use the static void Fl::screen_xywh (int &X, int &Y, int &W, int &H, int n) where n is the index of the screen you want to analyze, typically 0.
If all you care about is the screen below the mouse pointer, use the static void Fl::screen_xywh (int &X, int &Y, int &W, int &H) function.
I would like to generate random/noise points along each character of a multiple line text. I've tried this with the Geomerative library, but unfortunately it does not support multi line. Any other solution?
You could find a library to get the path points of the text or if simply adding points, you could get a 2D snapshot(either using get() or PGraphics) of the text and fill in pixels. Here's a minimal example.
PImage snapshot;
int randomSize = 3;
void setup(){
//render some text
background(255);
fill(0);
textSize(40);
text("Hello",0,50);
//grab a snapshot
snapshot = get();
}
void draw(){
int rx = (int)random(snapshot.width);//pick a random pixel location
int ry = (int)random(snapshot.height);//you can pick only the areas that have text or the whole image bot a bit of hit&miss randomness
//check if it's the same colour as the text, if so, pick a random neighbour and also paint it black
if(snapshot.get(rx,ry) == color(0)) snapshot.set(rx+((int)random(randomSize,-randomSize)),ry+((int)random(randomSize,-randomSize)),0);
image(snapshot,0,0);
}