Context Property (original) (raw)
Summary
Current graphics context associated with this object. For Windows Forms the type of this property is System.Drawing.Graphics. For WPF the type of this property is System.Windows.Media.DrawingContext.
Syntax
public Graphics Context { get; } public:
property System::Drawing::Graphics^ Context
{
System::Drawing::Graphics^ get()
}
Property Value
The graphics context associated with this object if any.
Example
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";
}