但是如果重写了drawRect:方法,这个方法会直接调用Core Graphics绘制方法得到bitmap 数据,同时系统会额外申请一块内存,用于暂存绘制好的bitmap。 由于重写了drawRect:方法,导致绘制过程从 GPU 转移到了 CPU,这就导致了一定的效率损失。与此同时,这个过程会额外使用 CPU 和内存,因此需要高效绘制,否则容易造成 CPU 卡顿...
在上一篇博客 【OpenGL】十、OpenGL 绘制点 ( 初始化 OpenGL 矩阵 | 设置投影矩阵 | 设置模型视图矩阵...
另一种方法称为9-slice scaling。矩形和纹理被分成9个切片。实际的舍入是在纹理的一角。想法是角不会...
voidMyCanvas2D::Render(System::Object^ sender, GLView::GLGraphics ^ Graphics) {//Draw a filled rectangleGraphics->FillRectangle(0.0f,0.0f,100.0f,50.0f, Drawing::Color::Red); } 实现,也可以使用Render事件内的原生OpenGL调用。兴趣点 如果实现窗体上的一个以上的实例GLCanvas2D,我们一定要确保正确的...
There are number of number of functions to define the path to draw, such as rectangle, rounded rectangle and ellipse, or you can use the common moveTo, lineTo, bezierTo and arcTo API to compose the paths step by step. Understanding Composite Paths Because of the way the rendering backend...
Having gone this far, it is a small step to switch from using lines to using triangle strips to draw the lines instead. One advantage of using lines is that many OpenGL implementations support antialiasing up to moderate line widths, whereas there is substantially less support for polygon anti...
open_window_in_double_buffer_mode();for(i = 0; i <1000000; i ++){clear_the_window();draw_frame(ⅰ);swap_the_buffers();} 刷新暂停 对于某些OpenGL实现,除了简单地交换可见和可绘制的缓冲区之外,swap_the_buffers()例程等待直到当前屏幕刷新周期结束,以便前一个缓冲区被完全显示。该例程也允许从一...
Initially, I did almost all functionalities ofPicZoomin a single class,CPicZoomDlg. It was very difficult to manage everything in a single class. Therefore, I prepared different classes based on different functionalities. For example,ImageAreaclass will handle all operations [draw, zoom, pan, mou...
#include <GL/gl.h> #include <GL/glut.h> void display(void) { /* clear all pixels */ glClear (GL_COLOR_BUFFER_BIT); /* draw white polygon (rectangle) with corners at * (0.25, 0.25, 0.0) and (0.75, 0.75, 0.0) */ glColor3f (1.0, 1.0, 1.0); glBegin(GL_POLYGON); glVertex...
There are number of number of functions to define the path to draw, such as rectangle, rounded rectangle and ellipse, or you can use the common moveTo, lineTo, bezierTo and arcTo API to compose the paths step by step. Understanding Composite Paths Because of the way the rendering backend...