WPF - Drawing on canvas with mouse events
I'm willing to bet that your canvas isn't receiving mouse events because it's background property is set to transparent
This works fine for me.
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Canvas Name="paintSurface" MouseDown="Canvas_MouseDown_1" MouseMove="Canvas_MouseMove_1" >
<Canvas.Background>
<SolidColorBrush Color="White" Opacity="0"/>
</Canvas.Background>
</Canvas>
</Window>
using System;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Input;
using System.Windows.Shapes;
namespace WpfApplication1
{
public partial class MainWindow : Window
{
Point currentPoint = new Point();
public MainWindow()
{
InitializeComponent();
}
private void Canvas_MouseDown_1(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
if (e.ButtonState == MouseButtonState.Pressed)
currentPoint = e.GetPosition(this);
}
private void Canvas_MouseMove_1(object sender, System.Windows.Input.MouseEventArgs e)
{
if (e.LeftButton == MouseButtonState.Pressed)
{
Line line = new Line();
line.Stroke = SystemColors.WindowFrameBrush;
line.X1 = currentPoint.X;
line.Y1 = currentPoint.Y;
line.X2 = e.GetPosition(this).X;
line.Y2 = e.GetPosition(this).Y;
currentPoint = e.GetPosition(this);
paintSurface.Children.Add(line);
}
}
}
}
Simple use the InkCanvas
<InkCanvas x:Name="InkCanvas" x:FieldModifier="public" Background="Transparent" Opacity="1" EditingMode="GestureOnly" ForceCursor="True" Cursor="Pen" >
<InkCanvas.DefaultDrawingAttributes>
<DrawingAttributes Color="White" Width="7" Height="7" />
</InkCanvas.DefaultDrawingAttributes>
</InkCanvas>
When using Line, thick line(line.StrokeThickness = 20) looks like this:
So I tried PolyLine and works fine.(from this example http://www.c-sharpcorner.com/uploadfile/mahesh/polyline-in-wpf/)
Canvas.MouseMove += (sender, args) =>
{
if (args.LeftButton == MouseButtonState.Pressed)
{
Polyline polyLine;
if (PathModeCanvas.Children.Count == 0)
{
polyLine = new Polyline();
polyLine.Stroke = new SolidColorBrush(Colors.AliceBlue);
polyLine.StrokeThickness = 10;
Canvas.Children.Add(polyLine);
}
polyLine = (Polyline)Canvas.Children[0];
Point currentPoint = args.GetPosition(Canvas);
polyLine.Points.Add(currentPoint);
}
};