LibGfx: Add BMPWriter

This utility allows you to create a BMP file from a bitmap

Libraries/LibGfx/BMPWriter.cpp

@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2020, Ben Jilks <benjyjilks@gmail.com>
+ * 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.
+ */
+
+#include <AK/Vector.h>
+#include <LibGfx/BMPWriter.h>
+#include <LibGfx/Bitmap.h>
+#include <cstring>
+
+namespace Gfx {
+
+constexpr int bytes_per_pixel = 3;
+
+#define FILE_HEADER_SIZE 14
+#define IMAGE_INFORMATION_SIZE 40
+#define PIXEL_DATA_OFFSET FILE_HEADER_SIZE + IMAGE_INFORMATION_SIZE
+
+class Streamer {
+public:
+    Streamer(u8* data)
+        : m_data(data)
+    {
+    }
+
+    void write_u8(u8 i)
+    {
+        *(m_data++) = i;
+    }
+
+    void write_u16(u16 i)
+    {
+        *(m_data++) = i & 0xFF;
+        *(m_data++) = (i >> 8) & 0xFF;
+    }
+
+    void write_u32(u32 i)
+    {
+        write_u16(i & 0xFFFF);
+        write_u16((i >> 16) & 0xFFFF);
+    }
+
+    void write_i32(i32 i)
+    {
+        write_u32(static_cast<u32>(i));
+    }
+
+private:
+    u8* m_data;
+};
+
+static ByteBuffer write_pixel_data(const RefPtr<Bitmap> bitmap, int pixel_row_data_size)
+{
+    int image_size = pixel_row_data_size * bitmap->height();
+    auto buffer = ByteBuffer::create_uninitialized(image_size);
+
+    int current_row = 0;
+    for (int y = bitmap->height() - 1; y >= 0; --y) {
+        auto* row = buffer.data() + (pixel_row_data_size * current_row++);
+        for (int x = 0; x < bitmap->width(); x++) {
+            auto pixel = bitmap->get_pixel(x, y);
+            row[x * bytes_per_pixel + 0] = pixel.blue();
+            row[x * bytes_per_pixel + 1] = pixel.green();
+            row[x * bytes_per_pixel + 2] = pixel.red();
+        }
+    }
+
+    return buffer;
+}
+
+static ByteBuffer compress_pixel_data(const ByteBuffer& pixel_data, BMPWriter::Compression compression)
+{
+    switch (compression) {
+    case BMPWriter::Compression::RGB:
+        return pixel_data;
+    }
+
+    ASSERT_NOT_REACHED();
+}
+
+ByteBuffer BMPWriter::dump(const RefPtr<Bitmap> bitmap)
+{
+    int pixel_row_data_size = (bytes_per_pixel * 8 * bitmap->width() + 31) / 32 * 4;
+    int image_size = pixel_row_data_size * bitmap->height();
+    auto buffer = ByteBuffer::create_uninitialized(PIXEL_DATA_OFFSET);
+
+    auto pixel_data = write_pixel_data(bitmap, pixel_row_data_size);
+    pixel_data = compress_pixel_data(pixel_data, m_compression);
+
+    int file_size = PIXEL_DATA_OFFSET + pixel_data.size();
+    Streamer streamer(buffer.data());
+    streamer.write_u8('B');
+    streamer.write_u8('M');
+    streamer.write_u32(file_size);
+    streamer.write_u32(0);
+    streamer.write_u32(PIXEL_DATA_OFFSET);
+
+    streamer.write_u32(IMAGE_INFORMATION_SIZE); // Header size
+    streamer.write_i32(bitmap->width());        // ImageWidth
+    streamer.write_i32(bitmap->height());       // ImageHeight
+    streamer.write_u16(1);                      // Planes
+    streamer.write_u16(bytes_per_pixel * 8);    // BitsPerPixel
+    streamer.write_u32((u32)m_compression);     // Compression
+    streamer.write_u32(image_size);             // ImageSize
+    streamer.write_i32(0);                      // XpixelsPerMeter
+    streamer.write_i32(0);                      // YpixelsPerMeter
+    streamer.write_u32(0);                      // TotalColors
+    streamer.write_u32(0);                      // ImportantColors
+
+    buffer.append(pixel_data.data(), pixel_data.size());
+    return buffer;
+}
+
+}

Libraries/LibGfx/BMPWriter.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2020, Ben Jilks <benjyjilks@gmail.com>
+ * 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/ByteBuffer.h>
+
+namespace Gfx {
+
+class Bitmap;
+
+class BMPWriter {
+public:
+    BMPWriter() = default;
+
+    ByteBuffer dump(const RefPtr<Bitmap>);
+
+    enum class Compression : u32 {
+        RGB = 0,
+    };
+
+    inline void set_compression(Compression compression) { m_compression = compression; }
+
+private:
+    Compression m_compression { Compression::RGB };
+};
+
+}

Libraries/LibGfx/CMakeLists.txt

@@ -2,6 +2,7 @@ set(SOURCES
     AffineTransform.cpp
     Bitmap.cpp
     BMPLoader.cpp
+    BMPWriter.cpp
     CharacterBitmap.cpp
     ClassicStylePainter.cpp
     ClassicWindowTheme.cpp