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Use new GetContext overloads #4814

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Apr 20, 2021
Merged

Use new GetContext overloads #4814

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75 changes: 39 additions & 36 deletions src/System.Windows.Forms.Primitives/src/System/Windows/Forms/DeviceContextHdcScope.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -146,59 +146,62 @@ public unsafe DeviceContextHdcScope(
bool applyTransform = applyGraphicsState.HasFlag(ApplyGraphicsProperties.TranslateTransform);
bool applyClipping = applyGraphicsState.HasFlag(ApplyGraphicsProperties.Clipping);

#pragma warning disable SYSLIB0016 // Type or member is obsolete
// This API is very expensive and cannot be called after GetHdc()
object[]? data = applyTransform || applyClipping ? (object[])graphics.GetContextInfo() : null;
#pragma warning restore SYSLIB0016 // Type or member is obsolete
Region? clipRegion = null;
PointF offset = default;
if (applyClipping)
{
graphics.GetContextInfo(out offset, out clipRegion);
}
else if (applyTransform)
{
graphics.GetContextInfo(out offset);
}

using Region? clipRegion = (Region?)data?[0];
using Matrix? worldTransform = (Matrix?)data?[1];
using (clipRegion)
{
applyTransform = applyTransform && !offset.IsEmpty;
applyClipping = clipRegion is not null;

// elements (XFORM) = [eM11, eM12, eM21, eM22, eDx, eDy], eDx/eDy specify the translation offset.
float[]? elements = applyTransform ? worldTransform?.Elements : null;
int dx = elements is not null ? (int)elements[4] : 0;
int dy = elements is not null ? (int)elements[5] : 0;
applyTransform = applyTransform && elements is not null && (dx != 0 || dy != 0);
using var graphicsRegion = applyClipping ? new Gdi32.RegionScope(clipRegion!, graphics) : default;
applyClipping = applyClipping && !graphicsRegion!.Region.IsNull;

using var graphicsRegion = applyClipping ? new Gdi32.RegionScope(clipRegion!, graphics) : default;
applyClipping = applyClipping && !graphicsRegion!.Region.IsNull;
HDC = (Gdi32.HDC)graphics.GetHdc();

HDC = (Gdi32.HDC)graphics.GetHdc();
if (saveHdcState || applyClipping || applyTransform)
{
_savedHdcState = Gdi32.SaveDC(HDC);
}

if (saveHdcState || applyClipping || applyTransform)
{
_savedHdcState = Gdi32.SaveDC(HDC);
}
if (applyClipping)
{
// If the Graphics object was created from a native DC the actual clipping region is the intersection
// beteween the original DC clip region and the GDI+ one - for display Graphics it is the same as
// Graphics.VisibleClipBounds.

if (applyClipping)
{
// If the Graphics object was created from a native DC the actual clipping region is the intersection
// beteween the original DC clip region and the GDI+ one - for display Graphics it is the same as
// Graphics.VisibleClipBounds.
RegionType type;

RegionType type;
using var dcRegion = new Gdi32.RegionScope(HDC);
if (!dcRegion.IsNull)
{
type = Gdi32.CombineRgn(graphicsRegion!, dcRegion, graphicsRegion!, Gdi32.RGN.AND);
if (type == RegionType.ERROR)
{
throw new Win32Exception();
}
}

using var dcRegion = new Gdi32.RegionScope(HDC);
if (!dcRegion.IsNull)
{
type = Gdi32.CombineRgn(graphicsRegion!, dcRegion, graphicsRegion!, Gdi32.RGN.AND);
type = Gdi32.SelectClipRgn(HDC, graphicsRegion!);
if (type == RegionType.ERROR)
{
throw new Win32Exception();
}
}

type = Gdi32.SelectClipRgn(HDC, graphicsRegion!);
if (type == RegionType.ERROR)
if (applyTransform)
{
throw new Win32Exception();
Gdi32.OffsetViewportOrgEx(HDC, (int)offset.X, (int)offset.Y, null);
}
}

if (applyTransform)
{
Gdi32.OffsetViewportOrgEx(HDC, dx, dy, null);
}
}

public static implicit operator Gdi32.HDC(in DeviceContextHdcScope scope) => scope.HDC;
Expand Down
17 changes: 7 additions & 10 deletions src/System.Windows.Forms/src/System/Windows/Forms/Internal/DrawingEventArgs.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -156,18 +156,15 @@ internal static void CheckGraphicsForState(Graphics? graphics, DrawingEventFlags
return;
}

#pragma warning disable SYSLIB0016 // Type or member is obsolete
// Check to see if we've actually corrupted the state
object[] data = (object[])graphics.GetContextInfo();
#pragma warning restore SYSLIB0016 // Type or member is obsolete
graphics.GetContextInfo(out PointF offset, out Region? clip);

using Region clipRegion = (Region)data[0];
using Matrix worldTransform = (Matrix)data[1];

float[] elements = worldTransform?.Elements!;
bool isInfinite = clipRegion.IsInfinite(graphics);
Debug.Assert((int)elements[4] == 0 && (int)elements[5] == 0, "transform has been modified");
Debug.Assert(isInfinite, "clipping as been applied");
using (clip)
{
bool isInfinite = clip?.IsInfinite(graphics) ?? true;
Debug.Assert(offset.IsEmpty, "transform has been modified");
Debug.Assert(isInfinite, "clipping as been applied");
}
}
}
}