/// <summary>
/// Overlays pixel data from another <see cref="BitmapBuffer"/>, with alpha blending.
/// </summary>
/// <param name="x">
/// The x-coordinate where to begin writing in this <see cref="BitmapBuffer"/>.</param>
/// <param name="y">
/// The y-coordinate where to begin writing in this <see cref="BitmapBuffer"/>.</param>
/// <param name="source">
/// Another <see cref="BitmapBuffer"/> containing the rectangle to overlay.</param>
/// <param name="bounds">
/// The pixel rectangle within the specified <paramref name="source"/> to overlay.</param>
/// <param name="color">
/// The <see cref="Color"/> to substitute for all <paramref name="source"/> pixels.</param>
/// <exception cref="ArgumentNullException">
/// <paramref name="source"/> is a null reference.</exception>
/// <remarks><para>
/// <b>Overlay</b> blends all <see cref="Pixels"/> elements within the specified <paramref
/// name="bounds"/> of the specified <paramref name="source"/> buffer with the corresponding
/// <see cref="Pixels"/> elements in this <see cref="BitmapBuffer"/>, starting with the
/// specified <paramref name="x"/> and <paramref name="y"/> coordinates.
/// </para><para>
/// <b>Overlay</b> calls <see cref="BitmapUtility.BlendPbgra32"/> to perform alpha blending
/// between the specified <paramref name="source"/> buffer (acting as the overlay) and this
/// <see cref="BitmapBuffer"/> (acting as the blending target). No coordinate checking is
/// performed.
/// </para><para>
/// <b>Overlay</b> substitutes the specified <paramref name="color"/> for the actual color
/// channels of each <paramref name="source"/> pixel, while using its alpha channel to
/// govern alpha blending with the corresponding <see cref="Pixels"/> element. The alpha
/// channel of the specified <paramref name="color"/> is ignored.</para></remarks>
public void Overlay(int x, int y, BitmapBuffer source, RectI bounds, Color color)
{
if (source == null)
{
ThrowHelper.ThrowArgumentNullException("source");
}
int sourceOffset = bounds.X + source._size.Width * bounds.Y;
int targetOffset = x + _size.Width * y;
for (int dy = 0; dy < bounds.Height; dy++)
{
for (int dx = 0; dx < bounds.Width; dx++)
{
uint p0 = source._pixels[sourceOffset + dx];
uint p1 = _pixels[targetOffset + dx];
// multiply color channels with source alpha
color.A = (byte)(p0 >> 24);
p0 = BitmapUtility.ColorToPbgra32(color);
_pixels[targetOffset + dx] = BitmapUtility.BlendPbgra32(p0, p1);
}
sourceOffset += source._size.Width;
targetOffset += _size.Width;
}
}
/// <summary>
/// Blends the specified pixel in the <see cref="BitmapBuffer"/> with the specified <see
/// cref="Color"/>.</summary>
/// <param name="x">
/// The x-coordinate of the pixel to blend with <paramref name="color"/>.</param>
/// <param name="y">
/// The y-coordinate of the pixel to blend with <paramref name="color"/>.</param>
/// <param name="color">
/// The <see cref="Color"/> to blend with the pixel at the specified location in the <see
/// cref="BitmapBuffer"/>.</param>
/// <remarks><para>
/// <b>BlendPixel</b> blends the <see cref="Pixels"/> element at the specified <paramref
/// name="x"/> and <paramref name="y"/> coordinates with the <see
/// cref="PixelFormats.Pbgra32"/> representation of the specified <paramref name="color"/>.
/// </para><para>
/// <b>BlendPixel</b> calls <see cref="BitmapUtility.BlendPbgra32"/> to perform alpha
/// blending between the specified <paramref name="color"/> (acting as the overlay) and this
/// <see cref="BitmapBuffer"/> (acting as the blending target). No coordinate checking is
/// performed.</para></remarks>
public void BlendPixel(int x, int y, Color color)
{
uint value = BitmapUtility.ColorToPbgra32(color);
int i = x + _size.Width * y;
_pixels[i] = BitmapUtility.BlendPbgra32(value, _pixels[i]);
}
/// <overloads>
/// Overlays pixel data from another <see cref="BitmapBuffer"/>.</overloads>
/// <summary>
/// Overlays pixel data from another <see cref="BitmapBuffer"/>, with alpha blending.
/// </summary>
/// <param name="x">
/// The x-coordinate where to begin writing in this <see cref="BitmapBuffer"/>.</param>
/// <param name="y">
/// The y-coordinate where to begin writing in this <see cref="BitmapBuffer"/>.</param>
/// <param name="source">
/// Another <see cref="BitmapBuffer"/> containing the rectangle to overlay.</param>
/// <param name="bounds">
/// The pixel rectangle within the specified <paramref name="source"/> to overlay.</param>
/// <exception cref="ArgumentNullException">
/// <paramref name="source"/> is a null reference.</exception>
/// <remarks><para>
/// <b>Overlay</b> blends all <see cref="Pixels"/> elements within the specified <paramref
/// name="bounds"/> of the specified <paramref name="source"/> buffer with the corresponding
/// <see cref="Pixels"/> elements in this <see cref="BitmapBuffer"/>, starting with the
/// specified <paramref name="x"/> and <paramref name="y"/> coordinates.
/// </para><para>
/// <b>Overlay</b> calls <see cref="BitmapUtility.BlendPbgra32"/> to perform alpha blending
/// between the specified <paramref name="source"/> buffer (acting as the overlay) and this
/// <see cref="BitmapBuffer"/> (acting as the blending target). No coordinate checking is
/// performed.</para></remarks>
public void Overlay(int x, int y, BitmapBuffer source, RectI bounds)
{
if (source == null)
{
ThrowHelper.ThrowArgumentNullException("source");
}
int sourceOffset = bounds.X + source._size.Width * bounds.Y;
int targetOffset = x + _size.Width * y;
for (int dy = 0; dy < bounds.Height; dy++)
{
for (int dx = 0; dx < bounds.Width; dx++)
{
uint p0 = source._pixels[sourceOffset + dx];
uint p1 = _pixels[targetOffset + dx];
_pixels[targetOffset + dx] = BitmapUtility.BlendPbgra32(p0, p1);
}
sourceOffset += source._size.Width;
targetOffset += _size.Width;
}
}
public void BlendPbgra32()
{
Assert.AreEqual(0x12345678, BitmapUtility.BlendPbgra32(0x00ABCDEF, 0x12345678));
Assert.AreEqual(0xFFABCDEF, BitmapUtility.BlendPbgra32(0xFFABCDEF, 0x12345678));
Assert.AreEqual(0xAF485058, BitmapUtility.BlendPbgra32(0x7F203040, 0x60504030));
}