Declaration
property OnDrawLayerBox: TIEDrawLayerBoxEvent;
Description
Occurs when a layer box must be painted (
LayersDrawBox must be enabled). If you handle this event the default behavior is disabled.
ABitmap is the destination bitmap and
layer is the layer index that we are drawing.
Use
Layers[].
ClientAreaBox rectangle to get actual rectangle coordinates.
See the LayerEditing\Layers demo for more details.
Note: You can also use
SetLayersBoxStyle to customize the layer box style
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
procedure Tfmain.ImageEnView1DrawLayerBox(Sender: TObject; ACanvas: TCanvas; LayerIndex: Integer);
begin
// Draw green rect
with ACanvas do
begin
Pen.Style := psSolid;
Pen.Width := 2;
Pen.mode := pmCopy;
Pen.Color := clGreen;
Brush.Style := bsClear;
with ImageEnView1.Layers[LayerIndex].ClientAreaBox do
Rectangle(Left-1, Top-1, Right+1, Bottom+1);
end;
end;
// Use an empty OnDrawLayerBox to prevent a selection box from being drawn around the current layer
procedure Tfmain.ImageEnView1DrawLayerBox(Sender: TObject; ACanvas: TCanvas; LayerIndex: Integer);
begin
//
end;
Compatibility Information
Prior to v8.0.0,
OnDrawLayerBox used a TBitmap rather than a TCanvas. You may need to remove the existing event and add the event handler again.
See Also
◼SetLayersBoxStyle◼SetLayersGripStyle◼LayersDrawBox◼TIELayer.VisibleBox◼OnDrawLayerGrip