Occurs after the view is rendered.
public event EventHandler<ImageViewerRenderEventArgs> PostRender
public:
event EventHandler<Leadtools::Controls::ImageViewerRenderEventArgs^>^ PostRender
For more information, refer to Image Viewer Rendering.
This example will show how to customize the view rendering to draw extra shapes with and without transformation.
Start with the ImageViewer example, remove all the code inside the example function (search for the "// TODO: add example code here" comment) and insert the following code:
using Leadtools;
using Leadtools.Controls;
using Leadtools.Codecs;
using Leadtools.Drawing;
using Leadtools.ImageProcessing;
using Leadtools.ImageProcessing.Color;
public void ImageViewerPostRender_Example()
{
// Clear all the images already the viewer
_imageViewer.Items.Clear();
// Use vertical view layout
_imageViewer.ViewLayout = new ImageViewerVerticalViewLayout();
// Make sure the item size is larger than the image size (thumbnails mode)
_imageViewer.ItemSize = LeadSize.Create(200, 200);
_imageViewer.ItemPadding = new Padding(8, 8, 8, 20);
_imageViewer.ImageBorderThickness = 1;
// Add 4 items to the viewer
using (var codecs = new RasterCodecs())
{
for (var page = 1; page <= 4; page++)
{
var item = new ImageViewerItem();
var fileName = Path.Combine(LEAD_VARS.ImagesDir, string.Format("ocr{0}.tif", page));
// Create a thumbnail from the image
using (var image = codecs.Load(fileName, page))
{
item.Image = image.CreateThumbnail(180, 180, 24, RasterViewPerspective.TopLeft, RasterSizeFlags.Resample);
}
item.Text = string.Format("Item {0}", page - 1);
_imageViewer.Items.Add(item);
}
}
// Render on the view
_imageViewer.PostRender += (sender, e) =>
{
// Rendering the whole view
var graphics = e.PaintEventArgs.Graphics;
// Blue ellipse at fixed position. This will stay the same and will not scroll or zoom
using (var brush = new SolidBrush(Color.FromArgb(128, Color.Blue)))
graphics.FillEllipse(brush, new Rectangle(0, 0, 100, 100));
// Red ellipse at relative position, this will scroll and zoom with the view
var gstate = graphics.Save();
var transform = _imageViewer.ViewTransform;
using (var matrix = new System.Drawing.Drawing2D.Matrix(
(float)transform.M11, (float)transform.M12, (float)transform.M21, (float)transform.M22,
(float)transform.OffsetX, (float)transform.OffsetY))
graphics.MultiplyTransform(matrix);
graphics.FillEllipse(Brushes.Red, new Rectangle(0, 0, 100, 100));
graphics.Restore(gstate);
};
// Render on each item
_imageViewer.PostRenderItem += (sender, e) =>
{
var item = e.Item;
var graphics = e.PaintEventArgs.Graphics;
var gstate = graphics.Save();
// Get the bounding rectangle for the image
var bounds = LeadRectD.Create(0, 0, item.Image.ImageWidth, item.Image.ImageHeight);
// Add the image transform to the graphics
var transform = _imageViewer.GetItemImageTransform(item);
using (var matrix = new System.Drawing.Drawing2D.Matrix(
(float)transform.M11, (float)transform.M12, (float)transform.M21, (float)transform.M22,
(float)transform.OffsetX, (float)transform.OffsetY))
graphics.MultiplyTransform(matrix);
// Red hilight on top of each item image
using (var brush = new SolidBrush(Color.FromArgb(128, Color.Red)))
graphics.FillRectangle(brush, (float)bounds.X, (float)bounds.Y, (float)bounds.Width, (float)bounds.Height);
graphics.Restore(gstate);
};
}
static class LEAD_VARS
{
public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images";
}
Parameter | Type | Description |
---|---|---|
sender | object | The source of the event. |
e | ImageViewerRenderEventArgs | The event data. |
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