I am trying to export a plot generated by my program in the form of a bitmap. No problem with creating a bitmap in memory (with CreateDIBSection) and saving it on the disk (using GDI+). To draw I have to use device context, and the only one that is easily available is compatible with the screen. So I create a compatible dc, select the bitmap I already created into this device context and I am ready to draw and print into the bitmap. And it works - but it gives me no control over the size of the plot (note: size of the plot, not size of the bitmap). If I understand correctly what is happening mapping modes follow DPI of the screen DC which in turn means size of the plot (and text I put on the plot) is different on different computers.
Is there any way of changing the DPI resolution for the device context? Or perhaps there exist a better way of doing what I am trying to do? Perfect solution would be to ask user for the pixel bitmap size and be able to draw a plot that nicely fits the bitmap.
You don't have to use device context to draw now that you already use Gdiplus over GDI. You just associate your Gdiplus::Graphics object with a Gdiplus::Bitmap instead of HDC. Units and transformations let alone bitmap size are all independent of the device. Hope that helps.
Gdiplus::Bitmap bitmap( L"miranda_kerr.png" ); // draw over existing
Gdiplus::Graphics graphics( &bitmap );
Gdiplus::Pen pen( Gdiplus::Color(255,0,0));
Gdiplus::Status status = graphics.DrawLine( &pen, 20, 20, 100, 500 );
//...
Related
I am getting my feet wet with JavaFX, and have a simple drawing program which writes to a Canvas using a PixelWriter. The program draws a pixel at a time, reflecting each pixel over a number of axes to create a growing and evolving pattern centered on the canvas:
The Canvas is in the Center region of a BorderPane, and I have written the code to resize the canvas when the application window is resized. That works OK.
However, I would like to re-center the image on the new resized canvas so that the drawing can continue to grow on the larger canvas. What might be the best approach?
My ideas/attempts so far:
Capture a snapshot of the canvas and write it back to the resized canvas, but that comes out blurry (a couple of code examples below).
I dug into GraphicsContext translations, but that does not seem to move the existing image, just adjusts future drawing.
Maybe instead of resizing the canvas, I make a huge canvas bigger than I would expect my app window to be, and center it over the center region of the border pane (perhaps using a viewport of some kind?) I'm not thrilled about the whole idea of making some arbitrarily huge canvas that I think will be big enough though. I don't want to get into scaling - I am using PixelWriter so that I get the crispest image without antialiasing and other processing.
My snapshot attempt looked like this, but was blurry:
SnapshotParameters params = new SnapshotParameters();
params.setFill(Color.WHITE);
WritableImage image = canvas.snapshot(params, null);
canvas.getGraphicsContext2D().drawImage(image, 50, 50);
The 50, 50 offset above is just for my testing/learning - I'll replace it with a proper computed offset once I get the basic copy working. From the post How to copy contents of one canvas to another? I played with the setFill() parameter, to no effect.
From the post How to save a high DPI snapshot of a JavaFX Canvas I tried the following code. It was more clear, but I have not been able to figure out how to find or compute the pixelScale to get the most accurate snapshot (the value 10 is just some number I typed in bigger than 1 to see how it reacted):
int pixelScale = 10;
WritableImage image = new WritableImage((int)Math.rint(pixelScale * canvas.getWidth()),(int)Math.rint(pixelScale * canvas.getHeight()));
SnapshotParameters params = new SnapshotParameters();
params.setTransform(Transform.scale(pixelScale, pixelScale));
params.setFill(Color.WHITE);
canvas.snapshot(params, image);
canvas.getGraphicsContext2D().drawImage(image, 50, 50);
Thanks for any direction y'all can point me in!
I'm making a game were you can set the background image yourself.
The selected image is resized to make it fit the purpose, and then i want to load the picture into pygame.
I've something like:
image = Image.open('file')
image.thumbnail(size, Image.ANTIALIAS)
And now I want to load image into pygame.
of course I can use:
image.save(outfile, "JPEG")
background = pygame.image.load('outfile')
Is there a nice way without having to save the image to my hard drive?
Or is it possible that pygame resizes the image?
You can use pygame.transform.scale() to resize an image:
pygame.transform.scale()
resize to new resolution
scale(Surface, (width, height), DestSurface = None) -> Surface
Resizes the Surface to a new resolution. This is a fast scale operation that does not sample the results.
An optional destination surface can be used, rather than have it create a new one. This is quicker if you want to repeatedly scale something. However the destination must be the same size as the (width, height) passed in. Also the destination surface must be the same format.
So you don't have to use PIL.
Recently I am writting game editor in my project. I want to implement a editor which has four viewport like 3ds max or other 3D software.
So, how to use opengles2 to render context on multi-window?
You can usually have multiple views with each having its own frame buffer. In this case all you need to do is bind the correct frame buffer before drawing to each of the views. You might also need to have different contexts for each view and setting them as current before drawing (also before binding the frame buffer). If you need multiple contexts you will need to find a way to share resources between them though.
Another approach is having a single view and simply using glViewport to draw to different parts. In this case you need to set glViewport for a specific part, setting ortho or frustum (if view segments are of different size) and that is it. For instance if you split the view with buffer having dimensions bWidth and bHeight into 4 equal rectangles and you want to refresh the top right:
glViewport(bWidth*.5f, .0f, bWidth*.5f, bWidth*.5f);
glOrthof(.0f, bWidth*.5f, bHeight*.5f, .0f, .1, 1.0); //same for each in this case
//do all the drawing
and when you are finished with all you want to update just present the frame buffer.
I have an icon with partial alpha (alpha values between 0 and 255) that I want to display using GDIPlus. When using the Bitmap constructor of GDI+ that takes the direct filename, the file displays properly. However, when loading from resource, it has a problem recognizing alpha. I looked on MSDN, and there are problems with alpha: http://msdn.microsoft.com/en-us/library/windows/desktop/ms536318.aspx. By retrieving the ICONINFO structure from the Icon, I can get rid of the fully transparent pixels, however, the partially transparent pixels still appear either as fully opaque or fully transparent.
I wanted to know how to create a Win32 Bitmap from an Icon in resource with the partial alpha values.
You can use LoadResource to get a pointer to the icon and and its image data. You can pass the pointer to the image data to the appropriate Bitmap constructor. This is a bit of a chore because icons have a peculiar resource format.
If possible, it would be simpler to store your image as a transparent (i.e. 32bpp argb) bitmap. In this case you can use LoadImage with LR_CREATEDIBSECTION.
Update
Apparently LoadIcon does load the alpha correctly. It would appear that the problem is GdiPlus not respecting the alpha when you construct a GdiPlus::Bitmap from an HICON. What you could do is:
Use LoadIcon to load the icon.
Use GetIconInfo to get the ICONINFO. hbmColor is the handle of the transparent bitmap.
Use GetDIBits to get the bitmap bits from hbmColor.
Pass the data to the Bitmap constructor that takes bits and understands alpha.
The alpha channel is disturbed after you call LoadIcon. The Win32 APIs that load icons, e.g. LoadIcon, LoadImage, etc. are well proven. They reliably load icons with partial alpha.
You need to investigate the code that executes after the icon has been loaded. I can't give you a solution or an explanation, but I am confident that LoadIcon is not the culprit.
I wanted to know how to create a Win32 Bitmap from an
Icon in resource with the partial alpha values.
Call GetIcon or GetImage to obtain an HICON. Then call GetIconInfo. The bitmap you need is in the hbmColor field of the ICONINFO struct.
I use GDI to create some custom textwidget. I draw directly to the screen, unbuffered.
now i'd like to implement some fast scrolling, that simply pixelshifts the respective part of the framebuffer (and only redraws the newly visible lines).
I noticed that for example the rich text controls does it like this. If i use some GDI drawing functions to directly draw to the framebuffer, over a rich text control, and then scroll the rich text, it will also scroll my drawing along with the text. so i assume the rich text simply pixelshifts it's part of the framebuffer.
I'd like to do the same, but don't know how to do so.
Can someone help? (independant of programming language))
thanks!
The ScrollWindowEx() API function is optimized to do this.
See BitBlt function:
The BitBlt function performs a
bit-block transfer of the color data
corresponding to a rectangle of pixels
from the specified source device
context into a destination device
context.
and the example at the end of its documentation: Capturing an Image:
You can use a bitmap to capture an
image, and you can store the captured
image in memory, display it at a
different location in your
application's window. [...]
In some cases, you may want your
application to capture images and
store them only temporarily. [...] To
store an image temporarily, your
application must call
CreateCompatibleDC to create a DC that
is compatible with the current window
DC. After you create a compatible DC,
you create a bitmap with the
appropriate dimensions by calling the
CreateCompatibleBitmap function and
then select it into this device
context by calling the SelectObject
function.
After the compatible device context is
created and the appropriate bitmap has
been selected into it, you can capture
the image. The BitBlt function
captures images. This function
performs a bit block transfer that is,
it copies data from a source bitmap
into a destination bitmap. [...]
To redisplay the image, call BitBlt a
second time, specifying the compatible
DC as the source DC and a window DC as
the target DC.