public static void DrawDragRectangles(Rectangle[] newRects, int indent)
{
if (newRects.Length > 0)
{
// Create the first region
IntPtr newRegion = CreateRectangleRegion(newRects[0], indent);
for (int index = 1; index < newRects.Length; index++)
{
// Create the extra region
IntPtr extraRegion = CreateRectangleRegion(newRects[index], indent);
// Remove the intersection of the existing and extra regions
Gdi32.CombineRgn(newRegion, newRegion, extraRegion, (int)Win32.CombineFlags.RGN_XOR);
// Remove unwanted intermediate objects
Gdi32.DeleteObject(extraRegion);
}
// Get hold of the DC for the desktop
IntPtr hDC = User32.GetDC(IntPtr.Zero);
// Define the area we are allowed to draw into
Gdi32.SelectClipRgn(hDC, newRegion);
Win32.RECT rectBox = new Win32.RECT();
// Get the smallest rectangle that encloses region
Gdi32.GetClipBox(hDC, ref rectBox);
IntPtr brushHandler = GetHalfToneBrush();
// Select brush into the device context
IntPtr oldHandle = Gdi32.SelectObject(hDC, brushHandler);
// Blit to screen using provided pattern brush and invert with existing screen contents
Gdi32.PatBlt(hDC,
rectBox.left,
rectBox.top,
rectBox.right - rectBox.left,
rectBox.bottom - rectBox.top,
(uint)RasterOperations.PATINVERT);
// Put old handle back again
Gdi32.SelectObject(hDC, oldHandle);
// Reset the clipping region
Gdi32.SelectClipRgn(hDC, IntPtr.Zero);
// Remove unwanted region object
Gdi32.DeleteObject(newRegion);
// Must remember to release the HDC resource!
User32.ReleaseDC(IntPtr.Zero, hDC);
}
}
public static void DrawDragOutline(Region region)
{
if (region == null)
{
return;
}
// Get hold of the DC for the desktop
IntPtr hDC = User32.GetDC(IntPtr.Zero);
// Define the area we are allowed to draw into
IntPtr hRegion = region.GetHrgn(Graphics.FromHdc(hDC));
Gdi32.SelectClipRgn(hDC, hRegion);
Win32.RECT rectBox = new Win32.RECT();
// Get the smallest rectangle that encloses region
Gdi32.GetClipBox(hDC, ref rectBox);
IntPtr brushHandler = GetHalfToneBrush();
// Select brush into the device context
IntPtr oldHandle = Gdi32.SelectObject(hDC, brushHandler);
// Blit to screen using provided pattern brush and invert with existing screen contents
Gdi32.PatBlt(hDC,
rectBox.left,
rectBox.top,
rectBox.right - rectBox.left,
rectBox.bottom - rectBox.top,
(uint)Win32.RasterOperations.PATINVERT);
// Put old handle back again
Gdi32.SelectObject(hDC, oldHandle);
// Reset the clipping region
Gdi32.SelectClipRgn(hDC, IntPtr.Zero);
Gdi32.DeleteObject(hRegion);
// Must remember to release the HDC resource!
User32.ReleaseDC(IntPtr.Zero, hDC);
}
public void CreateWithGraphicsBasedOnImageAppliesRequestedParameters()
{
using Bitmap b = new Bitmap(10, 10);
using Graphics g = Graphics.FromImage(b);
Rectangle clipRectangle = new Rectangle(1, 1, 5, 5);
using Region r = new Region(clipRectangle);
g.Clip = r;
Matrix transform = new Matrix();
transform.Translate(1.0f, 2.0f);
g.Transform = transform;
// Just the translation transform
using (var scope = new DeviceContextHdcScope(g, ApplyGraphicsProperties.TranslateTransform))
{
Gdi32.GetViewportOrgEx(scope, out Point origin);
Assert.Equal(new Point(1, 2), origin);
RECT clipRect = default;
RegionType regionType = Gdi32.GetClipBox(scope, ref clipRect);
Assert.Equal(RegionType.SIMPLEREGION, regionType);
Assert.Equal(new Rectangle(-1, -2, 10, 10), (Rectangle)clipRect);
Assert.Equal(g, scope.DeviceContext);
}
// Just the clipping
using (var scope = new DeviceContextHdcScope(g, ApplyGraphicsProperties.Clipping))
{
Gdi32.GetViewportOrgEx(scope, out Point origin);
Assert.Equal(new Point(0, 0), origin);
RECT clipRect = default;
RegionType regionType = Gdi32.GetClipBox(scope, ref clipRect);
Assert.Equal(RegionType.SIMPLEREGION, regionType);
Assert.Equal(clipRectangle, (Rectangle)clipRect);
Assert.Equal(g, scope.DeviceContext);
}
// Both
using (var scope = new DeviceContextHdcScope(g, ApplyGraphicsProperties.All))
{
Gdi32.GetViewportOrgEx(scope, out Point origin);
Assert.Equal(new Point(1, 2), origin);
RECT clipRect = default;
RegionType regionType = Gdi32.GetClipBox(scope, ref clipRect);
Assert.Equal(RegionType.SIMPLEREGION, regionType);
Assert.Equal(new Rectangle(0, -1, 5, 5), (Rectangle)clipRect);
Assert.Equal(g, scope.DeviceContext);
}
// Nothing
using (var scope = new DeviceContextHdcScope(g, ApplyGraphicsProperties.None))
{
Gdi32.GetViewportOrgEx(scope, out Point origin);
Assert.Equal(new Point(0, 0), origin);
RECT clipRect = default;
RegionType regionType = Gdi32.GetClipBox(scope, ref clipRect);
Assert.Equal(RegionType.SIMPLEREGION, regionType);
Assert.Equal(new Rectangle(0, 0, 10, 10), (Rectangle)clipRect);
Assert.Equal(g, scope.DeviceContext);
}
// Validating we've unlocked the graphics object
g.DrawLine(Pens.DarkBlue, default, default);