public static void BlitRender(this WriteableBitmap bmp, WriteableBitmap source, bool shouldClear = true, float opacity = 1f, GeneralTransform transform = null)
{
const int PRECISION_SHIFT = 10;
const int PRECISION_VALUE = (1 << PRECISION_SHIFT);
const int PRECISION_MASK = PRECISION_VALUE - 1;
using (BitmapContext destContext = bmp.GetBitmapContext())
{
if (transform == null) transform = new MatrixTransform();
var destPixels = destContext.Pixels;
int destWidth = destContext.Width;
int destHeight = destContext.Height;
var inverse = transform.Inverse;
if(shouldClear) destContext.Clear();
using (BitmapContext sourceContext = source.GetBitmapContext())
{
var sourcePixels = sourceContext.Pixels;
int sourceWidth = sourceContext.Width;
int sourceHeight = sourceContext.Height;
Rect sourceRect = new Rect(0, 0, sourceWidth, sourceHeight);
Rect destRect = new Rect(0, 0, destWidth, destHeight);
Rect bounds = transform.TransformBounds(sourceRect);
bounds.Intersect(destRect);
int startX = (int)bounds.Left;
int startY = (int)bounds.Top;
int endX = (int)bounds.Right;
int endY = (int)bounds.Bottom;
#if NETFX_CORE
Point zeroZero = inverse.TransformPoint(new Point(startX, startY));
Point oneZero = inverse.TransformPoint(new Point(startX + 1, startY));
Point zeroOne = inverse.TransformPoint(new Point(startX, startY + 1));
#else
Point zeroZero = inverse.Transform(new Point(startX, startY));
Point oneZero = inverse.Transform(new Point(startX + 1, startY));
Point zeroOne = inverse.Transform(new Point(startX, startY + 1));
#endif
float sourceXf = ((float)zeroZero.X);
float sourceYf = ((float)zeroZero.Y);
int dxDx = (int)((((float)oneZero.X) - sourceXf) * PRECISION_VALUE); // for 1 unit in X coord, how much does X change in source texture?
int dxDy = (int)((((float)oneZero.Y) - sourceYf) * PRECISION_VALUE); // for 1 unit in X coord, how much does Y change in source texture?
int dyDx = (int)((((float)zeroOne.X) - sourceXf) * PRECISION_VALUE); // for 1 unit in Y coord, how much does X change in source texture?
int dyDy = (int)((((float)zeroOne.Y) - sourceYf) * PRECISION_VALUE); // for 1 unit in Y coord, how much does Y change in source texture?
int sourceX = (int)(((float)zeroZero.X) * PRECISION_VALUE);
int sourceY = (int)(((float)zeroZero.Y) * PRECISION_VALUE);
int sourceWidthFixed = sourceWidth << PRECISION_SHIFT;
int sourceHeightFixed = sourceHeight << PRECISION_SHIFT;
int opacityInt = (int)(opacity * 255);
int index = 0;
for (int destY = startY; destY < endY; destY++)
{
index = destY * destWidth + startX;
int savedSourceX = sourceX;
int savedSourceY = sourceY;
for (int destX = startX; destX < endX; destX++)
{
if ((sourceX >= 0) && (sourceX < sourceWidthFixed) && (sourceY >= 0) && (sourceY < sourceHeightFixed))
{
// bilinear filtering
int xFloor = sourceX >> PRECISION_SHIFT;
int yFloor = sourceY >> PRECISION_SHIFT;
if (xFloor < 0) xFloor = 0;
if (yFloor < 0) yFloor = 0;
int xCeil = xFloor + 1;
int yCeil = yFloor + 1;
if (xCeil >= sourceWidth)
{
xFloor = sourceWidth - 1;
xCeil = 0;
}
else
{
xCeil = 1;
}
if (yCeil >= sourceHeight)
{
yFloor = sourceHeight - 1;
yCeil = 0;
}
else
{
yCeil = sourceWidth;
}
int i1 = yFloor * sourceWidth + xFloor;
int p1 = sourcePixels[i1];
int p2 = sourcePixels[i1 + xCeil];
int p3 = sourcePixels[i1 + yCeil];
int p4 = sourcePixels[i1 + yCeil + xCeil];
int xFrac = sourceX & PRECISION_MASK;
int yFrac = sourceY & PRECISION_MASK;
// alpha
byte a1 = (byte)(p1 >> 24);
byte a2 = (byte)(p2 >> 24);
byte a3 = (byte)(p3 >> 24);
byte a4 = (byte)(p4 >> 24);
int comp1, comp2;
byte a;
if ((a1 == a2) && (a1 == a3) && (a1 == a4))
{
if (a1 == 0)
{
destPixels[index] = 0;
sourceX += dxDx;
sourceY += dxDy;
index++;
continue;
}
a = a1;
}
else
{
comp1 = a1 + ((xFrac * (a2 - a1)) >> PRECISION_SHIFT);
comp2 = a3 + ((xFrac * (a4 - a3)) >> PRECISION_SHIFT);
a = (byte)(comp1 + ((yFrac * (comp2 - comp1)) >> PRECISION_SHIFT));
}
// red
comp1 = ((byte)(p1 >> 16)) + ((xFrac * (((byte)(p2 >> 16)) - ((byte)(p1 >> 16)))) >> PRECISION_SHIFT);
comp2 = ((byte)(p3 >> 16)) + ((xFrac * (((byte)(p4 >> 16)) - ((byte)(p3 >> 16)))) >> PRECISION_SHIFT);
byte r = (byte)(comp1 + ((yFrac * (comp2 - comp1)) >> PRECISION_SHIFT));
// green
comp1 = ((byte)(p1 >> 8)) + ((xFrac * (((byte)(p2 >> 8)) - ((byte)(p1 >> 8)))) >> PRECISION_SHIFT);
comp2 = ((byte)(p3 >> 8)) + ((xFrac * (((byte)(p4 >> 8)) - ((byte)(p3 >> 8)))) >> PRECISION_SHIFT);
byte g = (byte)(comp1 + ((yFrac * (comp2 - comp1)) >> PRECISION_SHIFT));
// blue
comp1 = ((byte)p1) + ((xFrac * (((byte)p2) - ((byte)p1))) >> PRECISION_SHIFT);
comp2 = ((byte)p3) + ((xFrac * (((byte)p4) - ((byte)p3))) >> PRECISION_SHIFT);
byte b = (byte)(comp1 + ((yFrac * (comp2 - comp1)) >> PRECISION_SHIFT));
// save updated pixel
if (opacityInt != 255)
{
a = (byte)((a * opacityInt) >> 8);
r = (byte)((r * opacityInt) >> 8);
g = (byte)((g * opacityInt) >> 8);
b = (byte)((b * opacityInt) >> 8);
}
destPixels[index] = (a << 24) | (r << 16) | (g << 8) | b;
}
sourceX += dxDx;
sourceY += dxDy;
index++;
}
sourceX = savedSourceX + dyDx;
sourceY = savedSourceY + dyDy;
}
}
}
}
