LibGfx: adding a very simple PNG writer

With this patch it is possible to create PNG files. Only minimal options
are supported. The PNG is created with one big IDAT chunk containing
only non-compressible DEFLATE blocks.

1 files changed, 50 insertions, 0 deletions

diff --git a/Userland/Libraries/LibGfx/PNGWriter.h b/Userland/Libraries/LibGfx/PNGWriter.h
new file mode 100644
index 0000000000..d07ed9d273
--- /dev/null
+++ b/Userland/Libraries/LibGfx/PNGWriter.h
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2021, Pierre Hoffmeister
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/String.h>
+#include <AK/Vector.h>
+#include <LibGfx/Bitmap.h>
+
+namespace Gfx {
+
+class PNGChunk;
+
+class PNGWriter {
+public:
+    ByteBuffer write(const RefPtr<Bitmap>);
+
+private:
+    Vector<u8> m_data;
+    void add_chunk(const PNGChunk&);
+    void add_png_header();
+    void add_IHDR_chunk(u32 width, u32 height, u8 bit_depth, u8 color_type, u8 compression_method, u8 filter_method, u8 interlace_method);
+    void add_IDAT_chunk(const RefPtr<Bitmap>);
+    void add_IEND_chunk();
+};
+
+}