dpi

1.使用C# 修改图片DPI private void Form1_DragDrop(object sender, DragEventArgs e) { if (e.Data.GetDataPresent(DataFormats.FileDrop)) { this.textBox1.Text = ((string[])e.Data.GetData(DataFormats.FileDrop.ToString()))[0]; } } private void textBox1_DragOver(object sender, DragEventArgs e) { e.Effect = DragDropEffects.Copy; } using (Bitmap newImage = new Bitmap(Image.FromFile(this.textBox1.Text))) { newImage.SetResolution(300, 300); newImage.Save("123.jpg", System.Drawing.Imaging.ImageFormat.Jpeg); } 上面是winform窗口拖拽文件，然后在修改图片DPI。测试成功，可以正常修改。 2. VC修改图片DPI 代码原理和C#一致，但是不能修改成功。 使用GDIPlus int GetImageCLSID

we can use DisplayMetrics.densityDpi to obtain a approximate dpi value of the device,but i eager to know how to obtain the exact dpi value? Use DisplayMatrics.xdpi and DisplayMatrics.ydpi xdpi The exact physical pixels per inch of the screen in the X dimension. ydpi The exact physical pixels per inch of the screen in the Y dimension. getResources().getDisplayMetrics().xdpi getResources().getDisplayMetrics().ydpi I think you can accesss this through the class DisplayMetrics and the field densityDpi . 来源： https://stackoverflow.com/questions/7594527/how-to-obtain-the-exact-dpi-value-of-android

I have a Logitech G500 gaming mouse that is running at its full DPI of 5700. I'm trying to write a program in C++ that accurately measures horizontal movement of the mouse in physical units, ie. centimetres or inches. I'm using the windows API and windows raw input via the WM_INPUT message to get raw movement changes from the mouse. I'm then assuming 1 unit of movement reported through WM_INPUT is 1/5700th of an inch, and as I'm tracking the net movement of the mouse, I thought I could perform a simple calculation to yield the net physical movement: distance(inches) = total_movement_from

i have an application from which i want to print an image. The image is loaded as a BufferedImage object. The problem is, when i print the image (to the postscript or to the pdf file), the quality is really poor. When i'm using some other tools (basically any picture viewer application which can print the image) the result is significantly better. I know there can be some problems with the DPI vs resolution but i'm not exactly sure how to compute the correct values for printing. I tried to google and tried some methods, but nothing seems to work as i expected. Basicaly i just want to print an