一眨眼2012就来了，真是时光飞逝~~由于工作需要，那就以这篇画板为2012的开篇吧 
关于画板这个东西，而且是简易画板，网上搜一下也是一箩筐一箩筐的，有些做得很不错，但那已经超出简易级别了：）属于简易级别的却没找到自己中意的
后来综合了几篇简易画板+自己的idea，造就了本Demo。闲话不多说，先上图
代码
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
namespace GDIDemo
{
public partial class Form1 : Form
{
Bitmap originImg;
Image finishImg;
Graphics g;
DrawType dType;
Point StartPoint, EndPoint, FontPoint;
Pen p = new Pen(Color.Black, 1);
bool IsDraw;
Font font;
Rectangle FontRect;
/// <summary>
/// 画笔颜色
/// </summary>
Color DrawColor
{
get { return p.Color; }
set { p.Color = value; }
}
/// <summary>
/// 画笔宽度
/// </summary>
float PenWidth
{
set { p.Width = value; }
}
public Form1()
{
InitializeComponent();
cmbThickness.SelectedIndex = 0;
//将文本输入框的父容器设为picDraw，否则显示时会出现错位
txtWrite.Parent = picDraw;
this.SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint, true);
this.UpdateStyles();
//将线帽样式设为圆线帽，否则笔宽变宽时会出现明显的缺口
p.StartCap = LineCap.Round;
p.EndCap = LineCap.Round;
originImg = new Bitmap(picDraw.Width, picDraw.Height);
g = Graphics.FromImage(originImg);
//画布背景初始化为白底
g.Clear(Color.White);
picDraw.Image = originImg;
finishImg = (Image)originImg.Clone();
}
private void btnArrow_Click(object sender, EventArgs e)
{
dType = DrawType.None;
txtWrite.Visible = false;
txtWrite.Text = "";
}
private void btnPen_Click(object sender, EventArgs e)
{
dType = DrawType.Pen;
txtWrite.Visible = false;
txtWrite.Text = "";
}
private void btnLine_Click(object sender, EventArgs e)
{
dType = DrawType.Line;
txtWrite.Visible = false;
txtWrite.Text = "";
}
private void btnRect_Click(object sender, EventArgs e)
{
dType = DrawType.Rect;
txtWrite.Visible = false;
txtWrite.Text = "";
}
private void btnEllipse_Click(object sender, EventArgs e)
{
dType = DrawType.Ellipse;
txtWrite.Visible = false;
txtWrite.Text = "";
}
private void btnEraser_Click(object sender, EventArgs e)
{
dType = DrawType.Eraser;
txtWrite.Visible = false;
txtWrite.Text = "";
}
private void btnWrite_Click(object sender, EventArgs e)
{
dType = DrawType.Write;
FontDialog fd = new FontDialog(); //写字前先选择字体
if (fd.ShowDialog() == DialogResult.OK)
{
font = fd.Font;
}
}
private void btnClear_Click(object sender, EventArgs e)
{
txtWrite.Visible = false;
txtWrite.Text = "";
g.Clear(Color.White);
reDraw();
}
private void picDraw_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
IsDraw = true;
StartPoint = e.Location;
switch (dType)
{
case DrawType.Pen:
case DrawType.Eraser:
finishImg = (Image)originImg.Clone();
break;
case DrawType.Write: //隐藏写字框
if (!txtWrite.Bounds.Contains(StartPoint))
{
txtWrite.Visible = false;
DrawString(txtWrite.Text);
txtWrite.Text = "";
return;
}
break;
}
}
}
private void picDraw_MouseMove(object sender, MouseEventArgs e)
{
if (IsDraw)
{
EndPoint = e.Location;
if (dType != DrawType.Pen && dType != DrawType.Eraser)
{
finishImg = (Image)originImg.Clone();
}
g = Graphics.FromImage(finishImg);
g.SmoothingMode = SmoothingMode.AntiAlias; //抗锯齿
switch (dType)
{
case DrawType.Line:
g.DrawLine(p, StartPoint, EndPoint);
break;
case DrawType.Pen:
g.DrawLine(p, StartPoint, EndPoint);
StartPoint = EndPoint;
break;
case DrawType.Rect:
Point leftTop = new Point(StartPoint.X, StartPoint.Y);
int width = Math.Abs(StartPoint.X - e.X), height = Math.Abs(StartPoint.Y - e.Y);
if (e.X < StartPoint.X)
leftTop.X = e.X;
if (e.Y < StartPoint.Y)
leftTop.Y = e.Y;
Rectangle rect = new Rectangle(leftTop, new Size(width, height));
g.DrawRectangle(p, rect);
break;
case DrawType.Ellipse:
leftTop = new Point(StartPoint.X, StartPoint.Y);
int Ewidth = Math.Abs(StartPoint.X - e.X), Eheight = Math.Abs(StartPoint.Y - e.Y);
if (e.X < StartPoint.X)
leftTop.X = e.X;
if (e.Y < StartPoint.Y)
leftTop.Y = e.Y;
rect = new Rectangle(leftTop, new Size(Ewidth, Eheight));
g.DrawEllipse(p, rect);
break;
case DrawType.Eraser:
Pen pen1 = new Pen(Color.White, 20);
pen1.StartCap = LineCap.Round;
pen1.StartCap = LineCap.Round;
g.DrawLine(pen1, StartPoint, EndPoint);
StartPoint = EndPoint;
pen1.Dispose();
break;
case DrawType.Write: //写字前画虚线框
leftTop = new Point(StartPoint.X, StartPoint.Y);
int w = Math.Abs(StartPoint.X - e.X);
int h = Math.Abs(StartPoint.Y - e.Y);
if (e.X < StartPoint.X)
leftTop.X = e.X;
if (e.Y < StartPoint.Y)
leftTop.Y = e.Y;
FontRect = new Rectangle(leftTop, new Size(w, h));
Pen pRect = new Pen(Color.Black);
pRect.DashPattern = new float[] { 4.0F, 2.0F, 1.0F, 3.0F };
g.DrawRectangle(pRect, FontRect);
pRect.Dispose();
break;
}
reDraw();
}
}
private void picDraw_MouseUp(object sender, MouseEventArgs e)
{
IsDraw = false;
originImg = (Bitmap)finishImg;
if (dType == DrawType.Write)
{
//清除虚线框
Pen pRect = new Pen(Color.White);
g.DrawRectangle(pRect, FontRect);
pRect.Dispose();
//写字文本框 呈现
txtWrite.SetBounds(FontRect.Left, FontRect.Top, FontRect.Width, FontRect.Height);
txtWrite.Font = font;
FontPoint = FontRect.Location;
txtWrite.Visible = true;
txtWrite.Focus();
}
//此句的作用是避免窗体最小化后还原窗体时，画布内容“丢失”
//其实没有丢失，只是没刷新而已，读者可以在画布任意处作画，便可还原画布内容
picDraw.Image = originImg;
}
/// <summary>
/// 重绘绘图区（二次缓冲技术）
/// </summary>
private void reDraw()
{
Graphics graphics = picDraw.CreateGraphics();
graphics.DrawImage(finishImg, new Point(0, 0));
graphics.Dispose();
}
/// <summary>
/// 在画布 写字
/// </summary>
/// <param name="str"></param>
private void DrawString(string str)
{
g.DrawString(str, font, new SolidBrush(DrawColor), FontPoint);
reDraw();
}
/// <summary>
/// 在画布 作画
/// </summary>
/// <param name="img"></param>
private void DrawImage(Image img)
{
g = Graphics.FromImage(finishImg);
g.DrawImage(img, new Point(0, 0));
reDraw();
}
private void btnImport_Click(object sender, EventArgs e)
{
txtWrite.Visible = false;
txtWrite.Text = "";
OpenFileDialog ofd = new OpenFileDialog();
ofd.Filter = "Image file(*.jpg;*.png;*.bmp)|*.jpg;*.png;*.bmp";
if (ofd.ShowDialog() == DialogResult.OK)
{
DrawImage(Image.FromFile(ofd.FileName));
}
}
private void btnExport_Click(object sender, EventArgs e)
{
txtWrite.Visible = false;
txtWrite.Text = "";
SaveFileDialog sfd = new SaveFileDialog();
sfd.Filter = "jpg|*.jpg|png|*.png|bmp|*.bmp";
if (sfd.ShowDialog() == DialogResult.OK)
{
finishImg.Save(sfd.FileName);
}
}
/// <summary>
/// 画笔颜色设置
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void btnColor_Click(object sender, EventArgs e)
{
ColorDialog cd = new ColorDialog();
cd.FullOpen = true;
cd.Color = DrawColor;
if (cd.ShowDialog() == DialogResult.OK)
{
DrawColor = cd.Color;
}
}
/// <summary>
/// 画笔宽度设置
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void cmbThickness_SelectedIndexChanged(object sender, EventArgs e)
{
PenWidth = Convert.ToSingle(cmbThickness.Text);
}
}
/// <summary>
/// 画笔类型
/// </summary>
enum DrawType
{
None,
Pen,
Line,
Rect,
Ellipse,
Eraser,
Write
}
}