How can I draw a rectangle that has two round corners and the opposite corners are rectangular corners. The shape must be closed so it can be filled with the Brush color. The Polyline method doesn't draw curved lines. Can I add the points of an Arc to the polyline points? I tried to draw a RoundRect using Canvas method and then, overlapping a rectangle over the lower round corners, but I couldn't figure out how to erase the upper line of the rectangle when drawign just the border of the shape without filling it. Note: if you think is relevant, I can add the code I used.
Sample of the desired shape:
Sample of what I got with Delphi:
You don't have to fill the shape at the same time you draw it. You can use a series of TCanvas.LineTo() and TCanvas.ArcTo()/TCanvas.AngleArc() calls first to create the shape, then call TCanvas.FloodFill() afterwards to fill it.
Otherwise, you can overlap TCanvas.Rectangle() on top of TCanvas.RoundRect() with the same fill color, and then use TCanvas.MoveTo()/TCanvas.LineTo() to draw over the dividing line with the same fill color.
Another option would be to forget using TCanvas drawing methods and just use Win32 API calls instead. Use CreateRoundRectRgn(), CreateRectRgn(), and CombineRn() to create a HRGN that has your desired shape, then use FillRgn() and FrameRgn() to draw on your TCanvas using that HRGN.
Related
I'm trying to draw a rounded rectangle with transparency with the library Skia.
I get a perfect result if i'm using overlapping without transparency.
But when i'm using transparency, i get this:
That's what i get when i do not overlap:
Even if i modify the radius of the inner rectancle, there're still some overlaps/gabs.
My questitons:
What is the correct way to caluclate the radius of the inner rectangle, when i can accept some missplaced pixels?
Is there another way?
You can use saveLayerAlpha before drawing and then restore after drawing. This allows you to draw multiple paths, shapes, etc with a "global" alpha applied to the layer.
I am working on API which requires me set up a outer geometry mask on ID2D1Rendertarget such that any draw call after that only draws portion of drawings which lies outside this geometry.
https://msdn.microsoft.com/en-us/library/windows/desktop/dd756675(v=vs.85).aspx explains how can we setup a inner geometry mask on ID2D1Rendertarget such that any draw call after that only draws portion of drawings which lies inside this geometry.I want to implement just opposite of that. Is this possible? Any help is deeply appreciated.
One way to do this is to subtract your geometry from a rectangle that fills the entire render target. Check out the MSDN page on combining geometries. I have a small code example below:
ComPtr<ID2D1PathGeometry> invertedGeometry;
ComPtr<ID2D1RectangleGeometry> rectangleGeometry;
d2dFactory->CreateRectangleGeometry(
{ 0, 0, targetWidth, targetHeight },
&rectangleGeometry
);
ComPtr<ID2D1GeometrySink> geometrySink;
d2dFactory->CreatePathGeometry(&invertedGeometry);
invertedGeometry->Open(&geometrySink);
rectangleGeometry->CombineWithGeometry(
pathGeometry.Get(),
D2D1_COMBINE_MODE_EXCLUDE,
D2D1::Matrix3x2F::Identity(),
geometrySink.Get()
);
geometrySink->Close();
Use the inverted geometry as the geometric mask instead of the original path geometry.
A second way to do this is to rasterize your geometry to a bitmap and use it as an opacity mask. You can flip the colors depending on whether or not you want the inside or outside to mask.
When I use CAShapeLayer and create a rectangle shape then the path starts at rectangle's origin (top-left corner) and draws clockwise. Now if I want to draw only part of the shape then I'm using strokeStart and strokeEnd properties. The problem comes when I want to draw a part consisting the path's end points. In this case the path is closed and it starts and ends on rectangle's top-left corner. When I'm setting strokeStart=0.8 and strokeEnd=0.2 I'm hoping it to draw the last section of the path and a bit from the beginning of the path. However, this is not working. Are there any ideas or tricks how to do this?
Update:
Adding an image to clarify what I mean above. I want an animation which draws a small amount of rectangle and that drawn part circles over the rectangle:
The short answer is that I don't think you can do that, at least not with a single path that will draw any of the segments in your examples. I'm pretty sure that strokeStart must be less than strokeEnd.
If you want to draw your last segment you'd need to create a custom rectangle path that started at the lower left corner and wrapped around.
I've used the CGContext based routine to fill a rectangle, but this time I actually want to fill all of a rectangle EXCEPT one part of it. I know this is possible in other drawing systems for other platofrm but can it be done with core graphics on iOS?
Both borderWidth and cornerRadius are animatable properties. So you could just animate them directly (using CABasicAnimation). In that rendering, you'd go from no border and no corners to having a border and corners in an animated way.
If you want to animate the rectangular tracing of the border, you'd need to use a CAShapeLayer (because the end of its path is animatable) and provide the illusion that way.
Let said I have a image which the circle in the middle is transparent and I use the drawRect function to draw sqaure like the second image below.
Then what I want to do is to get the alpha layer of the first image, the circle as a path, then apply on the square i draw and clip it and draw like the final image, just want it to draw on the circle path.
Thank in advance.