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Gtk3: rewritten TGtk3DeviceContext.getPixel() to return correct pixel e, especially when our surface is not an image. issue #41413

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zeljan1 2025-02-09 13:16:21 +01:00
parent 07d34d83e4
commit 03b43038f3
1 changed files with 81 additions and 9 deletions
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90
lcl/interfaces/gtk3/gtk3objects.pas
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@ -2004,21 +2004,93 @@ end;
function TGtk3DeviceContext.getPixel(x, y: Integer): TColor;
var
pixels,row: pointer;
stride:integer;
APixbuf: PGdkPixbuf;
AData: PByte;
APixelValue: LongWord;
ASurfaceWidth, ASurfaceHeight, ARowStride: Integer;
AOutSize: Tcairo_rectangle_int_t;
ARegion: Pcairo_region_t;
begin
Result := 0;
cairo_surface_flush (CairoSurface);
pixels := cairo_image_surface_get_data(Cairosurface);
if Assigned(pixels) then
if CairoSurface = nil then
exit;
if cairo_surface_get_type(CairoSurface) = CAIRO_SURFACE_TYPE_IMAGE then
begin
stride := cairo_image_surface_get_stride(CairoSurface);
row:=pixels+(fncOrigin.Y+Y)*stride;
inc(row,(fncOrigin.X+X)*sizeof(longint));
Result := PLongInt(row)^ and $FFFFFF; // take first 3 bytes at pixels^
ASurfaceWidth := cairo_image_surface_get_width(CairoSurface);
ASurfaceHeight := cairo_image_surface_get_height(CairoSurface);
end else
begin
ASurfaceWidth := 0;
ASurfaceHeight := 0;
//Our context have or GtkWidget or GdkWindow available.
if Assigned(Self.Parent) then
begin
ASurfaceWidth := gtk_widget_get_allocated_width(Self.Parent);
ASurfaceHeight := gtk_widget_get_allocated_height(Self.Parent);
end else
if Assigned(Self.Window) then
begin
//for now we'll use cairo region, it's faster than
//calculate client size by calling gdk_window_get_geometry() + gdk_window_get_frame_extents()
ARegion := gdk_window_get_clip_region(Self.Window);
if ARegion <> nil then
begin
cairo_region_get_extents(ARegion, @AOutSize);
ASurfaceWidth := AOutSize.width;
ASurfaceHeight := AOutSize.height;
cairo_region_destroy(ARegion);
end;
end;
end;
if (X < 0) or (Y < 0) or (X >= ASurfaceWidth) or (Y >= ASurfaceHeight) then
begin
DebugLn(Format('ERROR: TGtk3DeviceContext.getPixel: Pixel out of bounds x %d y %d surface width %d height %d !',
[x, y, ASurfaceWidth, ASurfaceHeight]));
Exit;
end;
if cairo_surface_get_type(CairoSurface) = CAIRO_SURFACE_TYPE_IMAGE then
begin
cairo_surface_flush(CairoSurface);
AData := PByte(cairo_image_surface_get_data(CairoSurface));
if AData <> nil then
begin
ARowStride := cairo_image_surface_get_stride(CairoSurface);
APixelValue := PLongWord(AData + (Y * ARowStride) + (X * 4))^;
Result := ((APixelValue and $00FF0000) shr 16) or
(APixelValue and $0000FF00) or
((APixelValue and $000000FF) shl 16);
exit;
end else
begin
DebugLn('Error: GetPixel for CAIRO_SURFACE_TYPE_IMAGE failed.');
exit(0);
end;
end;
APixbuf := gdk_pixbuf_get_from_surface(CairoSurface, X, Y, 1, 1);
if APixbuf = nil then
Exit;
AData := gdk_pixbuf_get_pixels(APixbuf);
ARowStride := gdk_pixbuf_get_rowstride(APixbuf);
APixelValue := PLongWord(AData)^;
Result := ((APixelValue and $FF0000) shr 16) or
(APixelValue and $00FF00) or
((APixelValue and $0000FF) shl 16);
g_object_unref(APixbuf);
end;
procedure TGtk3DeviceContext.drawRect(x1, y1, w, h: Integer; const AFill, ABorder: Boolean);
var
aOp: Tcairo_operator_t;