graphics

问题 I have a PictureBox with a picture as a background of an application, having all the Anchors set, so it can resize with the form. On this PictureBox, I am creating many other things, for now only rectangles. I am creating them on some X and Y coordinates, that is fine. Adding a picture to show what I am trying to do. Created rectangle is actually the little light blue square. But, when i resize the form, for example I maximize it, the rectangle stays at the same coordinates, which of course

问题 Looking for a way to resize a Labels text in line with the change in size of the Label . (ie. should a label increase in size by 50% , then the text should also increase in size by approx 50% ). There is plenty of articles around which adjust the text to fit fully within the size of a Label , which isn't suitable for what I want. I already have a working version of this. Somehow I need to be able to reference the previous size of a Label once the resize is complete in order to determine the

问题 I am using ImageMagick to programmatically reduce the size of a PNG image by reducing the colors in the image. I get the images unique-colors and divide this by 2. Then I assign this value to the -colors option as follows: variable = unique-colors / 2 convert image.png -colors variable -depth 8 I thought this would substantially reduce the size of the image but instead it increases the images size on disk. Can anyone shed any light on this. Thanks. EDIT: Turns out the problem was dithering.

问题 How do I change the color of only a subset of labels in a simple boxplot? For example, on the X-axis I have groups "3", "4", and "5", and I only want to change the color of the "4" group label. It's easy to change the color of the boxplot itself with the col="red", or even the border of the boxplot with border="red", but I cannot find any reference to changing JUST the label. Example: boxplot(mtcars$hp~mtcars$gear) Thanks! 回答1: You could also try mtext : b <- boxplot(count ~ spray, data =

问题 How do I change the color of only a subset of labels in a simple boxplot? For example, on the X-axis I have groups "3", "4", and "5", and I only want to change the color of the "4" group label. It's easy to change the color of the boxplot itself with the col="red", or even the border of the boxplot with border="red", but I cannot find any reference to changing JUST the label. Example: boxplot(mtcars$hp~mtcars$gear) Thanks! 回答1: You could also try mtext : b <- boxplot(count ~ spray, data =

问题 I have a large display (about 1000x2000 pixels) and I'm doing the following to draw images to the screen: QImage *pImage = GetImage(); // from wherever QPainter painter(this); painter.drawImage((0,0), *pImage); // this line takes over 100ms to complete. The larger the screen is that I'm drawing to, the longer this paint takes. I guess the pImage is being memcpy'd and that's the difference. How can I reduce this overhead? I'm not trying to scale or anything here. Thanks. 回答1: You're painting a

问题 How can i change the mouse pointer to an image when clicked on the image in c#? 回答1: The question is vague/unclear but perhaps you want to change the system cursor (not just your application)? Here is a link to the pinvoke info for SetSystemCursor. Be warned this is considered bad form. 回答2: This MSDN article explains how you would do it with WPF. Just change their drop-down to a OnClick for the image you're interested in. You could likely also hook in to an OnClick event in WinForms too, but

问题 How can i change the mouse pointer to an image when clicked on the image in c#? 回答1: The question is vague/unclear but perhaps you want to change the system cursor (not just your application)? Here is a link to the pinvoke info for SetSystemCursor. Be warned this is considered bad form. 回答2: This MSDN article explains how you would do it with WPF. Just change their drop-down to a OnClick for the image you're interested in. You could likely also hook in to an OnClick event in WinForms too, but

问题 What are the steps in feature-based registration? If I have a transformed image matching to a stack of images (of which only one is the best match), what are the steps in registration? Once I find matches and use them to estimate a transform, what's usually the next step? 回答1: Find points/areas which are invariant to different kind of transformations like: translation, rotation, scale.. because this points are invariant to those transformation we can find them in the different images that we

问题 I'm using the DCdensity function in the rdd package, which produces a plot of the density of a run variable in a regression discontinuity design, assuming the argument plot = TRUE . The help page says "The user may wrap this function in additional graphical options to modify the plot." I want to produce the default plot, but with larger axis title/tick font size, but I can't figure out how to do it. DCdensity doesn't accept additional arguments, and when I wrap the function call in plot() as