Declaration
property OnDrawLayerGrip: TIEDrawLayerGrip;
Description
Occurs when a layer grip is painted. If you handle this event the default behavior is disabled.
ABitmap is the destination bitmap and LayerIndex is the layer we are drawing.
Grip is in the range 0-9 as follows:
Value | Description |
0 | Left-top |
1 | Right-top |
2 | Right-bottom |
3 | Left-bottom |
4 | Left side |
5 | Right side |
6 | Top side |
7 | Bottom side |
8 | Rotation center grip |
9 | Rotation grip (grip that appears below the layer for easy rotation) |
Rect specifies the actual grip rectangle.
See the LayerEditing\Layers demo for more details.
ImageEnView Paint Events
The main paint events of TImageEnView are
OnDrawBackBuffer which occurs when the back buffer is painted and
OnDrawCanvas which occurs every time the canvas is painted. Generally
OnDrawBackBuffer is used for better performance, because the back buffer painting only occurs after the content is
updated. If you need constant custom drawing (e.g. to draw a marker at the current cursor position) then use
OnDrawCanvas.
In layer applications,
OnBeforeDrawLayer and
OnDrawLayer will occur while painting each individual layer. Use these methods if you need easy custom drawing upon each individual layer (e.g. a layer title). Generally
OnBeforeDrawLayer is best, unless you need to paint to the whole image (i.e. outside the area of the layer).
Other drawing events:
◼OnDrawBackground occurs when the background (area behind the image is painted) is painted to allow custom background styling
◼OnDrawLayerBox occurs when the
box around a
layer is painted to allow custom styling of the box
◼OnDrawLayerGrip occurs when the
grips of the selected
layer are drawn to allow custom grip styling
◼OnTransitionPaint occurs while
transitioning from one image to the next
◼OnPaint notifies whenever there is a paint event. It is not used for custom drawing
◼OnDrawPolygon notifies whenever a point of a polygonal selection is drawn
// Draw custom style grips
procedure Tfmain.ImageEnView1DrawLayerGrip(Sender: TObject;
ABitmap: TBitmap; layer, grip: Integer; rect: TRect);
begin
with ABitmap.Canvas do
begin
Pen.Style := psSolid;
Pen.Mode := pmCopy;
Pen.Color := clGreen;
Brush.Style := bsSolid;
Brush.Color := $0000FF00;
with rect do
Ellipse(Left-1, Top-1, Right+1, Bottom+1);
end;
end;
// Only draw corner grips
procedure Tfmain.ImageEnView1DrawLayerGrip(Sender: TObject;
ABitmap: TBitmap; layer, grip: Integer; rect: TRect);
begin
if grip in [0,1,2,3] then
begin
iec := TIECanvas.Create( ABitmap.Canvas );
IEDrawGrip( iec, rect, ImageEnView1.GetLayersGripStyle() );
iec.Free();
end;
end;
See Also
◼GetLayersGripStyle◼SetLayersBoxStyle◼SetLayersGripStyle◼LayersDrawBox◼TIELayer.VisibleBox◼OnDrawLayerBox