Various optimisations to speed up LZWDecoder
- Take advantage of the fact that we add new codes in the order they are
discovered so no need to store the code as part of a separate
CodeTableEntry structure. Instead we store directly store vectors of
colors and the code is the index into the vector.
- Cache current table capacity to avoid calling pow2 every time.
- Prevent some unnecessary vector copies by returning by reference from
get_output.
Adds methods to determine whether an image is animated, how many times
the animation loops, the number of frames, and to get individual frames.
Implements stubs of these methods for PNGImageDecoderPlugin and
GIFImageDecoderPlugin.
The existing scanline method works just fine, and only needs the points
to be available as floats.
This commit reverts the complex polygon mitigation, and instead fixes
the rasterization process to avoid generating complex polygons because
of precision issues.
This allows the painter to render filled complex shapes better, by
constructing a path graph for (interesting) intersecting lines and
omitting lines from the containing segments if they are detected
to take no part in defining the edges of a shape.
This approach would still fail if there are multiple logical shapes
that are confined to the collection of lines.
For instance, two polygons intersecting each other in a way that one
vertex of polygon A ends up inside polygon B.
we would detect that polygon A's edges are part of the shape
(technically correct) even though they are not a part of polygon B at
all.
There are some imperfections with intersecting edges (because the main
algorithm used is scanline, and that is not geared towards drawing
complex shapes), however, it behaves mostly fine for normal use :^)
When dealing with png data that has less than 8 bits per pixel, round
up to the next byte when allocating per row buffers and streamers. This
fixes decoding odd sized PNGs with less than 8 bits per pixel.
Also added a test page with some odd sized palleted PNGs.
The LZW decode step will now copy and pad LZW data out to 4 bytes if there are
less than 4 bytes remaining in the buffer. This means it will now also work when
the total size of the LZW image data is less than 4 bytes.
The sniff method is intended to be used for content sniffing. It should be a
cheap test to rapidly rule out whether a candidate image can be successfully
decoded. For the GIF and PNG implementations it simply attempts to decode the
image header, returning true if successful and false if not.
Also:
- Define the GIFLoadingContext structure.
- The load_gif_impl function now returns load operation success, and takes a
reference to a GIFLoadingContext as input.
- Implement GIFImageDecoderPlugin::bitmap which calls onto load_gif_impl.
This will be used to implement painting of 2D paths. This first patch
adds support for line_to(), move_to() and close().
It will try to have the same semantics as the HTML <canvas> element.
To stroke a Path, simply pass it to Painter::stroke_path().
If the area or size_in_bytes calculation for a Gfx::Bitmap would
overflow, we now refuse to create such a bitmap and return nullptr.
Thanks to @itamar8910 for finding this! :^)
blit_filtered() can be used to easily implement per-pixel filtered blit
functions. All you need to do is provide a callback that can compute
the Color for each pixel based on the original Color.
With this patch, it's now possible to pass a Gfx::ShareableBitmap in an
IPC message. As long as the message itself is synchronous, the bitmap
will be adopted by the receiving end, and disowned by the sender nicely
without any accounting effort like we've had to do in the past.
Use this in NotificationServer to allow sending arbitrary bitmaps as
icons instead of paths-to-icons.
Instead of passing the BufferStream, pass the Decoder. I'd like to stop
using BufferStream eventually anyway, so it's good to get it out of any
API's where it's in currently.
