Init

MainForm/ZoomFactor.cs

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+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Drawing;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace ImageCompressor
+{
+
+
+    /// <summary>
+    /// 计算保存Zoom的数据
+    /// </summary>
+    class ZoomFactor
+    {
+        static double zoomPercent = 0.1;
+        /// <summary>
+        /// [0.1 - 1]
+        /// 对原图像的最短一边的像素 * value，作为新方形图像的一边像素值。
+        /// </summary>
+        public static double ZoomPercent
+        {
+            get
+            {
+                return zoomPercent;
+            }
+            set
+            {
+                if (value < 0.01) zoomPercent = 0.01;
+                else if (value > 1) zoomPercent = 1;
+                else zoomPercent = value;
+            }
+        }
+        /// <summary>
+        /// 新图像宽度的百分比
+        /// </summary>
+        double widthLocationPercent;
+        /// <summary>
+        /// 新图像高度的百分比
+        /// </summary>
+        double heightLocationPercent;
+
+
+        public Rectangle GetSourceImage(Image image)
+        {
+            int rawImageHeight= image.Height;
+            int rawImageWidth= image.Width;
+            int NewImageX = (int)(rawImageWidth * widthLocationPercent);
+            int NewImageY = (int)(rawImageHeight * heightLocationPercent);
+            int NewImageSize = (int)(Math.Min(rawImageHeight, rawImageWidth) * zoomPercent);
+            return new Rectangle(NewImageX - NewImageSize/2, NewImageY - NewImageSize / 2, NewImageSize, NewImageSize);
+        }
+
+        /// <summary>
+        /// 获取当前缩放数据
+        /// </summary>
+        /// <param name="previewBoxRectangle"></param>
+        /// <param name="location"></param>
+        /// <param name="imageWidth"></param>
+        /// <param name="imageHeight"></param>
+        public ZoomFactor(Rectangle previewBoxRectangle, Point location, int imageWidth, int imageHeight)
+        {
+            double X = location.X; // - previewBoxRectangle.X;
+            double Y = location.Y;// - previewBoxRectangle.Y;
+            if ((double)imageWidth / (double)imageHeight > (double)previewBoxRectangle.Width / (double)previewBoxRectangle.Height)
+            {
+                double truePreviewBoxHeight = previewBoxRectangle.Width * ((double)imageHeight / (double)imageWidth);
+                double offsetY = (previewBoxRectangle.Height - truePreviewBoxHeight) * 0.5;
+                //图像比预览框更宽
+                widthLocationPercent = X / (double)previewBoxRectangle.Width;
+                heightLocationPercent = (Y - offsetY) / truePreviewBoxHeight;
+            }
+            else
+            {
+                double truePreivewBoxWidth = previewBoxRectangle.Height * ((double)imageWidth / (double)imageHeight);
+                double offsetX = (previewBoxRectangle.Width - truePreivewBoxWidth) * 0.5;
+                widthLocationPercent = (X - offsetX) / truePreivewBoxWidth;
+                heightLocationPercent = Y / (double)previewBoxRectangle.Height;
+            }
+
+            //Debug.WriteLine("On Move percent w = {0}, h = {1}", widthLocationPercent, heightLocationPercent);
+        }
+    }
+
+}