SkiaSharp 是一个强大的跨平台 2D 图形库，提供了灵活且高效的图像处理能力。本文将深入探讨 SkiaSharp 中图像裁剪的各种技术和方法。
Nuget 安装包
C#SkiaSharp SkiaSharp.Views.WindowsForms
基本图像裁剪
核心功能
- 图像打开：支持打开JPG、JPEG、PNG和BMP格式的图像文件
- 交互式选择区域：用户可以通过鼠标在图像上拖拽选择要裁剪的矩形区域
- 实时预览：选择过程中实时显示选择框和区域尺寸信息
- 图像裁剪：使用SkiaSharp库执行图像裁剪操作
- 裁剪结果保存：支持将裁剪后的图像保存为新文件
SkiaSharp 提供了强大的图像处理能力，其中图像旋转是最常用的操作之一。本文将深入探讨SkiaSharp中图像旋转的多种方法和技巧。
Nuget 安装包
C#SkiaSharp SkiaSharp.Views.WindowsForms
基本旋转方法
简单角度旋转
C#using System.Windows.Forms;
using SkiaSharp;
namespace AppRotation
{
public partial class Form1 : Form
{
private SKBitmap originalBitmap;
private string currentImagePath;
public Form1()
{
InitializeComponent();
}
private void btnLoad_Click(object sender, EventArgs e)
{
using (OpenFileDialog openFileDialog = new OpenFileDialog())
{
openFileDialog.Filter = "Image Files|*.png;*.jpg;*.jpeg;*.bmp;*.gif";
if (openFileDialog.ShowDialog() == DialogResult.OK)
{
currentImagePath = openFileDialog.FileName;
using (var fileStream = new FileStream(currentImagePath, FileMode.Open))
{
originalBitmap = SKBitmap.Decode(fileStream);
UpdateRotatedImage(pic, tbAngle.Value);
btnSave.Enabled = true;
}
}
}
}
private void tbAngle_Scroll(object sender, EventArgs e)
{
lblAngle.Text = $"Rotation Angle: {tbAngle.Value}°";
if (originalBitmap != null)
{
UpdateRotatedImage(pic, tbAngle.Value);
}
}
private void btnSave_Click(object sender, EventArgs e)
{
if (originalBitmap == null) return;
using (SaveFileDialog saveFileDialog = new SaveFileDialog())
{
saveFileDialog.Filter = "PNG Image|*.png|JPEG Image|*.jpg|BMP Image|*.bmp";
saveFileDialog.DefaultExt = "png";
saveFileDialog.AddExtension = true;
if (saveFileDialog.ShowDialog() == DialogResult.OK)
{
using (SKBitmap rotatedBitmap = RotateImage(originalBitmap, tbAngle.Value))
{
using (SKImage image = SKImage.FromBitmap(rotatedBitmap))
using (SKData data = image.Encode(SKEncodedImageFormat.Png, 100))
using (FileStream stream = new FileStream(saveFileDialog.FileName, FileMode.Create))
{
data.SaveTo(stream);
}
}
MessageBox.Show("Image saved successfully!", "Success", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
}
}
private void UpdateRotatedImage(PictureBox pic, int angle)
{
if (originalBitmap == null) return;
using (SKBitmap rotatedBitmap = RotateImage(originalBitmap, angle))
{
using (SKImage image = SKImage.FromBitmap(rotatedBitmap))
using (SKData data = image.Encode())
using (MemoryStream memStream = new MemoryStream())
{
data.SaveTo(memStream);
memStream.Position = 0;
if (pic.Image != null)
{
pic.Image.Dispose();
}
pic.Image = new Bitmap(memStream);
}
}
}
public SKBitmap RotateImage(SKBitmap originalBitmap, float angle)
{
// 创建一个新的位图，大小适应旋转后的图像
SKBitmap rotatedBitmap = new SKBitmap(
(int)(Math.Abs(originalBitmap.Width * Math.Cos(angle * Math.PI / 180)) +
Math.Abs(originalBitmap.Height * Math.Sin(angle * Math.PI / 180))),
(int)(Math.Abs(originalBitmap.Width * Math.Sin(angle * Math.PI / 180)) +
Math.Abs(originalBitmap.Height * Math.Cos(angle * Math.PI / 180)))
);
using (SKCanvas canvas = new SKCanvas(rotatedBitmap))
{
// Clear canvas with transparent background
canvas.Clear(SKColors.Transparent);
// 将画布中心移动到图像中心
canvas.Translate(rotatedBitmap.Width / 2f, rotatedBitmap.Height / 2f);
// 旋转画布
canvas.RotateDegrees(angle);
// 绘制原始图像，使其居中
canvas.DrawBitmap(originalBitmap,
new SKPoint(-originalBitmap.Width / 2f, -originalBitmap.Height / 2f));
}
return rotatedBitmap;
}
}
}
SkiaSharp 提供了多种强大的图像缩放方法，可以满足不同场景下的图像处理需求。本文将详细探讨 SkiaSharp 中图像缩放的各种技术和最佳实践。
Nuget 安装包
C#SkiaSharp SkiaSharp.Views.WindowsForms
基本缩放方法
等比例缩放
C#using System.Windows.Forms;
using SkiaSharp;
namespace AppImageScaling
{
public partial class Form1 : Form
{
private SKBitmap originalImage;
public Form1()
{
InitializeComponent();
}
private void btnLoad_Click(object sender, EventArgs e)
{
using (OpenFileDialog openFileDialog = new OpenFileDialog())
{
openFileDialog.Filter = "Image Files|*.bmp;*.jpg;*.jpeg;*.png;*.gif";
if (openFileDialog.ShowDialog() == DialogResult.OK)
{
originalImage = SKBitmap.Decode(openFileDialog.FileName);
SKBitmap scaledImage = ScaleImageProportionally(originalImage, 400);
pic.Image = BitmapFromSKBitmap(scaledImage);
}
}
}
public SKBitmap ScaleImageProportionally(SKBitmap originalImage, int targetWidth)
{
// 计算等比例缩放的高度
float aspectRatio = (float)originalImage.Height / originalImage.Width;
int targetHeight = (int)(targetWidth * aspectRatio);
// 创建缩放后的位图
SKBitmap scaledBitmap = new SKBitmap(targetWidth, targetHeight);
// 使用高质量缩放
using (SKCanvas canvas = new SKCanvas(scaledBitmap))
{
canvas.SetMatrix(SKMatrix.CreateScale(
(float)targetWidth / originalImage.Width,
(float)targetHeight / originalImage.Height
));
// 绘制原始图像
canvas.DrawBitmap(originalImage, 0, 0);
}
return scaledBitmap;
}
private Bitmap BitmapFromSKBitmap(SKBitmap skBitmap)
{
using (var image = SKImage.FromBitmap(skBitmap))
using (var data = image.Encode(SKEncodedImageFormat.Png, 100))
using (var stream = new System.IO.MemoryStream(data.ToArray()))
{
return new Bitmap(stream);
}
}
}
}
SkiaSharp 是一个强大的跨平台 2D 图形库，提供了丰富的图像处理能力。本文将深入探讨 SkiaSharp 中图像的加载、保存和基本操作。
Nuget 安装包
C#SkiaSharp SkiaSharp.Views.WindowsForms
图像加载基础
从文件加载图像
C#using System.Drawing;
using System.Windows.Forms;
using SkiaSharp;
using SkiaSharp.Views.Desktop;
namespace AppLoadSave
{
public partial class Form1 : Form
{
private SKBitmap loadedBitmap;
public Form1()
{
InitializeComponent();
}
// 从文件加载图像的方法
private SKBitmap LoadImageFromFile(string filePath)
{
try
{
// 使用 SKBitmap.Decode 方法加载图像
using (var stream = System.IO.File.OpenRead(filePath))
{
return SKBitmap.Decode(stream);
}
}
catch (Exception ex)
{
MessageBox.Show($"图像加载错误: {ex.Message}", "错误"
, MessageBoxButtons.OK, MessageBoxIcon.Error);
return null;
}
}
private Bitmap SKBitmapToSystemBitmap(SKBitmap skBitmap)
{
// 创建一个新的 Bitmap，使用 SKBitmap 的宽度和高度
Bitmap bitmap = new Bitmap(skBitmap.Width, skBitmap.Height,
System.Drawing.Imaging.PixelFormat.Format32bppPArgb);
// 锁定位图的位图数据
System.Drawing.Imaging.BitmapData bmpData = bitmap.LockBits(
new Rectangle(0, 0, bitmap.Width, bitmap.Height),
System.Drawing.Imaging.ImageLockMode.WriteOnly,
bitmap.PixelFormat);
// 复制像素数据
IntPtr ptr = bmpData.Scan0;
int bytes = Math.Abs(bmpData.Stride) * bitmap.Height;
byte[] rgbValues = new byte[bytes];
// 从 SKBitmap 获取像素数据
byte[] skPixels = skBitmap.Bytes;
// 转换颜色通道（BGRA to ARGB）
for (int i = 0; i < skPixels.Length; i += 4)
{
rgbValues[i] = skPixels[i + 2]; // B
rgbValues[i + 1] = skPixels[i + 1]; // G
rgbValues[i + 2] = skPixels[i]; // R
rgbValues[i + 3] = skPixels[i + 3]; // A
}
// 将像素数据复制到位图
System.Runtime.InteropServices.Marshal.Copy(rgbValues, 0, ptr, bytes);
bitmap.UnlockBits(bmpData);
return bitmap;
}
private void btnLoad_Click(object sender, EventArgs e)
{
using (OpenFileDialog openFileDialog = new OpenFileDialog())
{
openFileDialog.Filter = "图像文件|*.jpg;*.jpeg;*.png;*.bmp;*.gif";
openFileDialog.Title = "选择图像文件";
if (openFileDialog.ShowDialog() == DialogResult.OK)
{
// 加载图像
loadedBitmap = LoadImageFromFile(openFileDialog.FileName);
if (loadedBitmap != null)
{
// 直接从 SKBitmap 创建 Bitmap
Bitmap bitmap = SKBitmapToSystemBitmap(loadedBitmap);
pic.Image = bitmap;
}
}
}
}
}
}
文本渲染基础
SkiaSharp 提供了丰富的文本渲染和特效能力，让开发者可以创造出极具视觉吸引力的文字效果。本文将深入探讨 SkiaSharp 中文本特效的各种技巧和方法。
Nuget 安装包
C#SkiaSharp SkiaSharp.Views.WindowsForms
基本文本绘制
C#public void DrawSimpleText(SKCanvas canvas)
{
// 创建画笔
using var paint = new SKPaint
{
TextSize = 50,
Color = SKColors.Black,
IsAntialias = true,
Typeface = SKTypeface.FromFamilyName("Arial")
};
// 绘制基础文本
canvas.DrawText("Hello SkiaSharp", 50, 100, paint);
}
