Declaration

TIECanvas = class;

Description

TIECanvas is a GDI+ Graphics wrapper and VCL TCanvas wrapper.
It is available via TIEBitmap.IECanvas or by creating it from a TBitmap or TCanvas.

  

Methods and Properties

General

Draw Methods

Fill Methods

Text Methods

Advanced Draw Methods

Transformation Methods

Examples

// Draw an envelope with 50% transparency
with ImageEnView1.IEBitmap.IECanvas do
begin
  Pen.Mode := pmCopy;
  Pen.Style := psSolid;
  Pen.Color := clBlack;
  Pen.Transparency := 128;

  Brush.Color := clYellow;
  Brush.Style := bsSolid;
  Brush.Transparency := 128;

  // Draw outer rect
  Rectangle( 100, 100, 500, 300 );

  // Draw flap
  MoveTo( 100, 100 );
  LineTo( 300, 200 );
  LineTo( 500, 100 );
end;
ImageEnView1.Update();


// Draw an anti-aliased ellipse onto a TBitmap
iec := TIECanvas.Create( ABitmap.Canvas );
with iec do
begin
  Pen.Style := psSolid;
  Pen.Mode := pmCopy;
  Pen.Color := clRed;
  Brush.Style := bsClear
  Ellipse( Rect( 100, 100, 200, 200 ));
end;
iec.Free;


// Fill image with a vertical gradient from Red to Blue
ImageEnView1.IEBitmap.IECanvas.GradientFillRect( Rect( 0, 0, ImageEnView1.IEBitmap.Width, ImageEnView1.IEBitmap.Height ), clRed, clBlue, gpgVertical );
ImageEnView1.Update();


// Draw a semi-transparent text box onto a bitmap
const
  Horz_Margin = 8;
  Vert_Margin = 3;
  Center_Text = False;
var
  x, y: integer;
  tw, rw, rh: integer;
  iec: TIECanvas;
  ss: string;
begin
  ss := 'This is my text';
  x := 100;
  y := 100;

  iec := TIECanvas.Create( Bitmap.Canvas );

  iec.Font.Assign( GetTextFont() );
  tw := iec.TextWidth(ss);
  rw := imax( tw + 2 * Horz_Margin, iec.TextWidth(minText) + 2 * Horz_Margin );
  rh := iec.TextHeight(ss) + 2 * Vert_Margin;

  if Center_Text then
    dec( x, rw div 2 );

  iec.Brush.Color := clYellow;
  iec.Brush.Style := bsSolid;
  iec.Brush.Transparency := 196;

  iec.Pen.Color := clBlack;
  iec.Pen.Style := psSolid;
  iec.Rectangle( x, y, x + rw, y + rh );

  iec.Brush.Style := bsClear;
  iec.TextOut(x + ( rw - tw ) div 2, y + Vert_Margin, ss);
  iec.Free;
end;


// Highlight an area of a bitmap
iec := TIECanvas.Create( Bitmap.Canvas, false );
iec.Brush.Color := clRed;
iec.Brush.Style := bsSolid;
iec.Brush.Transparency := 125;
iec.FillRect( Rect( 100, 100, 300, 300 );
iec.Free;


// Draw a rounded, semi-transparent scrollbar (anti-aliased)
const
  RX = 12; // round width
  RY = 12; // round height
  MINSLIDERW = 8; // minimum slider width
var
  scrollPos, scrollCount: integer;
  sliderWidth: double;
begin
  x := 100;
  y := 100;
  Width := 300;
  Height := 16;
  scrollCount := 20;
  scrollPos := 3;

  with ImageEnView1.IEBitmap.IECanvas do
  begin
    // paint brush and border
    Brush.Style := bsSolid;
    Brush.Color := clWhite;
    Brush.Transparency := 64;
    Pen.Color := clWhite;
    Pen.Style := psSolid;
    Pen.Mode := pmCopy;
    Pen.Width := 1;
    Pen.Transparency := 128;
    RoundRect( x, y, x + width, y + height, RX, RY );

    // paint slider
    Brush.Style := bsSolid;
    Brush.Color := clBlack;
    Brush.Transparency := 128;
    Pen.Width := 1;
    Pen.Transparency := 128;
    sliderWidth := width / scrollCount;
    if sliderWidth < MINSLIDERW then
      sliderWidth := MINSLIDERW;
    RoundRect( x + trunc(scrollPos * sliderWidth), y + 1, x + trunc(scrollPos * sliderWidth) + trunc(asliderWidth), y + height - 1, RX, RY);
    end;
end;


// Draw an arrow at the end of a line that runs from x1, y1 to x2, y2
// brush and color must be already set
procedure IEDrawLineArrow(Canvas: TIECanvas; x1, y1, x2, y2: integer; w, h: integer);
const
  A90 = PI / 2;
var
  aa, bb, hw: double;
  pp: array[0..2] of TPoint;
  p1x, p1y: integer;
begin
  with Canvas do
  begin
    hw := w / 2;
    aa := IEAngle(x1, y1, x2, y2, x1, y2);
    if x1 = x2 then
      if y1 < y2 then
        aa := -A90
      else
        aa := A90;
    if ((x1 > x2) and (y2 < y1)) or ((x1 < x2) and (y1 < y2)) then
      bb := 2 * pi - aa + A90
    else
      bb := aa + A90;
    if ((x2 < x1) and (y2 > y1)) or ((x2 < x1) and (y2 < y1)) or ((x1 < x2) and (y1 = y2)) then
    begin
      p1x := x1 + trunc(cos(bb - A90) * h);
      p1y := y1 + trunc(sin(bb - A90) * h);
    end
    else
    begin
      p1x := x1 + trunc(cos(bb + A90) * h);
      p1y := y1 + trunc(sin(bb + A90) * h);
    end;

    pp[0].x := p1x + trunc(cos(bb) * hw);
    pp[0].y := p1y + trunc(sin(bb) * hw);
    pp[1].x := p1x + trunc(cos(bb + pi) * hw);
    pp[1].y := p1y + trunc(sin(bb + pi) * hw);
    pp[2].x := x1;
    pp[2].y := y1;

    Polygon(pp);
  end;
end;


// Draw one of ImageEn's predefined shapes
procedure IEDrawShape(Canvas: TIECanvas;
                      Shape: TIEShape;
                      Left, Top, Width, Height: Integer; MaintainAspect: TIEBooleanEx;
                      BorderColor: TColor; BorderWidth: Integer;
                      FillColor: TColor; FillColor2: TColor = clNone; FillGradient: TIEGDIPlusGradient = gpgVertical;
                      AntiAlias: Boolean = True;
                      Angle: Integer = 0;
                      ShapeModifier: Integer = 0);
var
  arPts : Array[ 0 .. Max_Shape_Array_Points ] of TPoint;
  drawPts : Array[ 0 .. Max_Shape_Array_Points ] of TPoint;
  currX, currY: Integer;
  exWidth, exHeight: Integer;
  i: Integer;
  ptCount: Integer;
begin
  IEGenerateShapePoints( arPts, ptCount, Shape, 0, 0, 1000, 1000,
                         Angle, False,
                         ShapeModifier,
                         Width / Height );

  if BorderColor = clNone then
    BorderWidth := 0;

  exWidth := imax( 0, ( Width - BorderWidth ));
  exHeight := imax( 0, ( Height - BorderWidth ));

  for i := 0 to ptCount - 1 do
  begin
    currX := arPts[ i ].x;
    currY := arPts[ i ].y;

    drawPts[i].x := Left + BorderWidth div 2 + round( currX / 1000 * exWidth );
    drawPts[i].y := Top + BorderWidth div 2 + round( currY / 1000 * exHeight );
  end;

  // PAINT TO CANVAS
  if AntiAlias then
    Canvas.SmoothingMode := iesmAntialias
  else
    Canvas.SmoothingMode := iesmBestPerformance;

  with Canvas do
  begin
    if BorderWidth > 0 then
    begin
      Pen.Style := psSolid;
      Pen.Width := BorderWidth;
      Pen.Color := BorderColor;
    end
    else
      Pen.Style := psClear;
    Pen.Mode := pmCopy;
    Pen.LineJoin := ieljRound;

    if FillColor = clNone then
      Brush.Style := bsClear
    else
    begin
      Brush.Color := FillColor;
      Brush.Style := bsSolid;
    end;

    if FillColor2 = clNone then
      Brush.SetGradient( gpgNone, 0, 0 )
    else
    begin
      Brush.SetGradient( FillGradient, Width, Height );
      Brush.BackTransparency := 255;
      Brush.BackColor := FillColor2;
    end;

    Polygon( slice( drawpts, ptCount ));
  end;
end;


// Draw an ellipse
procedure IEDrawSimpleShape(Canvas: TIECanvas;
                            Left, Top, Width, Height: Integer;
                            BorderColor: TColor; BorderWidth: Integer;
                            FillColor: TColor; FillColor2: TColor = clNone;
                            FillGradient: TIEGDIPlusGradient = gpgVertical;
                            ZoomX: Double = 1; ZoomY: Double = 1;
                            AntiAlias: Boolean = True);
const
  Rect_Rounding = 20;
var
  drawGradient: Boolean;
  minZoom: Double;
begin
  drawGradient := ( FillGradient <> gpgNone ) and
                  ( FillColor2 <> FillColor ) and
                  ( FillColor <> clNone ) and ( FillColor2 <> clNone );

  if AntiAlias then
    Canvas.SmoothingMode := iesmAntialias
  else
    Canvas.SmoothingMode := iesmBestPerformance;

  // Image has been scaled to zoom level, so ensure we scale the border too
  if BorderColor = clNone then
    BorderWidth := 0;
  if BorderWidth > 0 then
    BorderWidth := max( 1, Round( BorderWidth * minZoom ));

  // Border
  if ( BorderColor = clNone_ ) or ( BorderWidth < 1 ) then
    Canvas.Pen.Style := psClear
  else
    Canvas.Pen.Style := psSolid;
  Canvas.Pen.Color := BorderColor;
  Canvas.Pen.Width := BorderWidth;

  // Fill
  if ( FillColor = clNone_ ) then
    Canvas.Brush.Style := bsClear
  else
    Canvas.Brush.Style := bsSolid;
  Canvas.Brush.Color := FillColor;

  inc( Left , BorderWidth div 2 );
  inc( Top , BorderWidth div 2 );
  dec( Width , BorderWidth );
  dec( Height, BorderWidth );

  if drawGradient = False then
    Canvas.Brush.SetGradient( gpgNone, 0, 0 )
  else
  begin
    Canvas.Brush.SetGradient( FillGradient, Width, Height );
    Canvas.Brush.BackTransparency := 255;
    Canvas.Brush.BackColor := FillColor2;
  end;

  Canvas.Ellipse( Left, Top, Left + Width, Top + Height );
end;


// Draw text within a specified area onto a TIEBitmap
procedure TextOutEx(aBMP: TIEBitmap;
                    X, Y, W, H : Integer; const Text : String;
                    const sFontName : String; iFontSize : Integer; cFontColor : TColor; Style : TFontStyles;
                    Angle : Integer = 0;
                    bAntiAlias : Boolean = true; bAutoEnlarge : Boolean = False);
var
  AnExtent: TSize;
  Mask: TIEMask;
  x1, y1, x2, y2: Integer;
  CompCanvas: TIECanvas;
  iAlpha: Integer;
begin
  aBMP.Canvas.Font.Name := sFontName;
  aBMP.Canvas.Font.Size := iFontSize;
  aBMP.Canvas.Font.Color := cFontColor;
  aBMP.Canvas.Font.Style := Style;

  AnExtent := aBMP.IECanvas.MeasureText( Text );

  if Angle <> 0 then
    AnExtent := IERotatePoint2( AnExtent.cx, AnExtent.cy, Angle );

  if bAutoEnlarge and (( aBMP.Width < AnExtent.cx ) or ( aBMP.Height < AnExtent.cy )) then
  begin
    iAlpha := 255;
    if aBMP.HasAlphaChannel then
      iAlpha := aBMP.Alpha[0, 0];
    aBMP.Resize( iMax( aBMP.Width, AnExtent.cx ), iMax( aBMP.Height, AnExtent.cy ), Background, iAlpha);
  end;

  CompCanvas := aBMP.CreateROICanvas(Rect(0, 0, aBMP.Width, aBMP.Height), bAntiAlias, true, bAntiAlias);
  try
    if not bAntiAlias then // Cannot use together with alpha composting
      CompCanvas.TextRendering := ietrTextRenderingHintSingleBitPerPixel;

    CompCanvas.Brush.Color := aBMP.Canvas.Font.Color;
    CompCanvas.Font.Color := aBMP.Canvas.Font.Color;
    CompCanvas.Font.Name := aBMP.Canvas.Font.Name;
    CompCanvas.Font.Height := aBMP.Canvas.Font.Height;
    CompCanvas.Font.Style := aBMP.Canvas.Font.Style;

    if ( W = 0 ) and ( H = 0 ) then
      CompCanvas.DrawText( Text, X, Y, -Angle )
    else
      CompCanvas.DrawText( Text, Rect( X, Y, X + W, Y + H ), -Angle );
  finally
    CompCanvas.Free();
  end;
end;

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