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LCL/graphutil: Add procedure BitmapGrayscale to convert a bitmap to gray-scale with weighting of color channels (provided by Roland Hahn).

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This commit is contained in:
wp_xyz 2022-11-03 13:28:42 +01:00
parent e64a5bdd44
commit 9db6c1220c
1 changed files with 55 additions and 2 deletions
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57
lcl/graphutil.pp
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@ -21,7 +21,7 @@ unit GraphUtil;
interface
uses
Types, Math,
SysUtils, Types, Math,
// LCL
Graphics, LCLType, LCLIntf,
// LazUtils
@ -60,6 +60,9 @@ procedure DrawGradientWindow(Canvas: TCanvas; WindowRect: TRect; TitleHeight: In
procedure AntiAliasedStretchDrawBitmap(SourceBitmap, DestBitmap: TCustomBitmap;
DestWidth, DestHeight: integer);
{ Converts a bitmap to grayscale taking filtering parameters into account. }
procedure BitmapGrayscale(ABitmap: TCustomBitmap; RedFilter, GreenFilter, BlueFilter: Single);
{ Draw arrows }
type TScrollDirection=(sdLeft,sdRight,sdUp,sdDown);
TArrowType = (atSolid, atArrows);
@ -87,7 +90,7 @@ procedure WaveTo(ADC: HDC; X, Y, R: Integer);
implementation
uses
fpcanvas, IntfGraphics, LazCanvas;
fpimage, fpcanvas, IntfGraphics, LazCanvas;
//TODO: Check code on endianess
@ -518,6 +521,56 @@ begin
end;
end;
{ Converts a bitmap to grayscale by taking filtering parameters into account
Examples:
BitmapGrayscale(Image1.Picture.Bitmap, 0.30, 0.59, 0.11); // Neutral filter
BitmapGrayscale(Image1.Picture.Bitmap, 1.00, 0.00, 0.00); // Red filter
BitmapGrayscale(Image1.Picture.Bitmap, 0.00, 1.00, 0.00); // Green filter
BitmapGrayscale(Image1.Picture.Bitmap, 0.00, 0.00, 1.00); // Blue filter
BitmapGrayscale(Image1.Picture.Bitmap, 0.00, 0.50, 0.50); // Cyan filter
BitmapGrayscale(Image1.Picture.Bitmap, 0.50, 0.00, 0.50); // Magenta filter
BitmapGrayscale(Image1.Picture.Bitmap, 0.50, 0.50, 0.00); // Yellow filter
}
procedure BitmapGrayscale(ABitmap: TCustomBitmap; RedFilter, GreenFilter, BlueFilter: Single);
var
IntfImg: TLazIntfImage = nil;
x, y: Integer;
TempColor: TFPColor;
Gray: Word;
sum: Single;
begin
// Normalize filter factors to avoid word overflow.
sum := RedFilter + GreenFilter + BlueFilter;
if sum = 0.0 then
exit;
RedFilter := RedFilter / sum;
GreenFilter := GreenFilter / sum;
BlueFilter := BlueFilter / sum;
IntfImg := ABitmap.CreateIntfImage;
try
IntfImg.BeginUpdate;
try
for y := 0 to IntfImg.Height - 1 do
for x := 0 to IntfImg.Width - 1 do
begin
TempColor := IntfImg.Colors[x, y];
Gray := word(Round(TempColor.Red * RedFilter + TempColor.Green * GreenFilter + TempColor.Blue * BlueFilter));
TempColor.Red := Gray;
TempColor.Green := Gray;
TempColor.Blue := Gray;
IntfImg.Colors[x, y] := TempColor;
end;
finally
IntfImg.EndUpdate;
end;
ABitmap.LoadFromIntfImage(IntfImg);
finally
IntfImg.Free;
end;
end;
procedure WaveTo(ADC: HDC; X, Y, R: Integer);
var
Direction, Cur: Integer;