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* Fix bug ID #35124, add some informational properties to PNG reader

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git-svn-id: trunk@42876 -
This commit is contained in:
michael 2019-08-30 07:21:02 +00:00
parent def80285e6
commit 0461d35137
1 changed files with 52 additions and 0 deletions
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52
packages/fcl-image/src/fpreadpng.pp
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@ -26,6 +26,8 @@ Type
TSetPixelProc = procedure (x,y:integer; CD : TColordata) of object;
TConvertColorProc = function (CD:TColorData) : TFPColor of object;
{ TFPReaderPNG }
TFPReaderPNG = class (TFPCustomImageReader)
private
@ -46,6 +48,11 @@ Type
FPalette : TFPPalette;
FSetPixel : TSetPixelProc;
FConvertColor : TConvertColorProc;
function GetGrayScale: Boolean;
function GetHeaderByte(AIndex: Integer): Byte;
function GetIndexed: Boolean;
function GetUseAlpha: Boolean;
function GetWordSized: Boolean;
procedure ReadChunk;
procedure HandleData;
procedure HandleUnknown;
@ -99,6 +106,17 @@ Type
public
constructor create; override;
destructor destroy; override;
// These 2 match writer properties. Calculated from header values
Property GrayScale : Boolean Read GetGrayScale;
Property WordSized : Boolean Read GetWordSized;
Property Indexed : Boolean Read GetIndexed;
Property UseAlpha : Boolean Read GetUseAlpha;
// Raw reader values
Property BitDepth : Byte Index 0 Read GetHeaderByte;
Property ColorType : Byte Index 1 Read GetHeaderByte;
Property Compression : Byte Index 2 Read GetHeaderByte;
Property Filter : Byte Index 3 Read GetHeaderByte;
Property Interlace : Byte Index 4 Read GetHeaderByte;
end;
implementation
@ -176,6 +194,40 @@ begin
end;
end;
function TFPReaderPNG.GetHeaderByte(AIndex: Integer): Byte;
begin
With FHeader do
Case aIndex of
0 : Result:=BitDepth;
1 : Result:=ColorType;
2 : Result:=Compression;
3 : Result:=Filter;
4 : Result:=Interlace;
else
Result:=0;
end;
end;
function TFPReaderPNG.GetIndexed: Boolean;
begin
Result:=ColorType=3;
end;
function TFPReaderPNG.GetUseAlpha: Boolean;
begin
Result:=ColorType in [4,6]; // Can also be in 3, but that would require scanning the palette
end;
function TFPReaderPNG.GetWordSized: Boolean;
begin
Result:=BitDepth=16;
end;
function TFPReaderPNG.GetGrayScale: Boolean;
begin
Result:=ColorType in [0,4];
end;
procedure TFPReaderPNG.HandleData;
var OldSize : longword;
begin