paint()-mehod faster while mouse is moved - java

I am currently working on a private project that uses a normal java JFrame, in which I paint an image (in form of an int[][] with ARGB-values). Then I plot this image pixel by pixel inside the paint()-method. I have to do this, because I want to shift/zoom the image to my liking.
When I enlarge the window to my screen size (2560*1600) one run takes about 10 secs.
Doing the same whilst just moving the mouse around this time decreases to ca. 1.5 secs. Has anyone an explanation for this 7-time boost?
Thanks!
Bike

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Best way to draw a scrolling curved path onto a canvas

I want to create an illusion of a moving road or path.
For fun, I was thinking about how this could be done:
draw the whole path out in an image and simply have the image scroll across the screen - this would be annoying to manually draw and eliminates the ability to have a random path.
generate a pixel thin line equal the to width of the path at the top of the screen and simply move the line down the screen to have it scroll. And constantly generate new lines at the top in a slightly different location.
This is all I could come up with, I'm sure there are much better ways. How would y'all do it?
What about making a queue which stores the path with a maximum size. And then you just redraw it when it gets updated.
I think drawing the line again is comparable to drawing a full screen image in performance concerns. Furthermore it will take less memory.

Does java graphics render only the window size or everything?

I am making a 2d path-geometry based game in java. If I have a bunch of large shapes (Path2D's) that I am rendering every frame, is java taking the time to process the whole thing, or is it only processing the parts actually in the window?
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Thanks in advance!
Rendering is clipped to the visible portion only.
Obviously.
The clip area of the Graphics2D (see getClip()) is set automatically to the visible portion, but at some moment "Java" will still "take time" to determine whether the generic shapes are inside this clip area.
So it might be a valid optimization technique if you don't draw the shapes that are outside the visible area. Or you could draw the static shapes to an image, and then render this image.
After receiving some information, I decided to test it myself.
I made a complex shape using Path2D and rendered with the whole shape inside the window. Then, I rendered the same thing 90% outside the window, with only a small part of the shape showing.
The one that was outside the window showed much higher performance (260 FPS) than the one entirely in the window (50 FPS).
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I'm working on a 2D game in Java using swing JFrame.
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Android - Turn off Smoothness for Drawing on a Canvas using Bitmaps and Matrices

I have some very small images (20 by 20 pixels) which I am drawing using matrices onto a canvas using Canvas.drawBitmap(Bitmap, Matrix, Paint). The problem is that I am scaling these up about 5-10 times larger when I am drawing them and it is automatically re-sampling these images with smoothness. What I want is nearest-neighbour style re-sampling (so it will look pixelated) not the smoothness. I cannot find a way to change this. Also creating another whole image that is larger to store a properly re-sampled picture is not an option since I am under memory constraints. Thanks for any help!
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I have an application that displays plots using JFreeChart. As it happens, these plots are big and JFreeChart is not terribly fast, resulting in atrocious redraw times, particularly when resizing the plot.
What I am after is a way to stretch an image representing the plot while resizing (a bit like the iPhone will present a screenshot of a stopped application while it gets started again), and perform a full redraw only after the user has released the mouse (i.e. once the final size of the plot is known).
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Cheers
No concrete answer, just a possible strategy
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in JDK 7, you can use a JLayer for the image/manipulation.
Edit
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