如何使用Perl和GD创建透明的真彩色PNG？(How do you create a transparent truecolor PNG with Perl & GD?)

如何使用Perl和GD创建透明的真彩色PNG？(How do you create a transparent truecolor PNG with Perl & GD?)

这似乎是一个微不足道的问题，但我尝试过的任何事情都不会使背景变得透明。

use strict; use warnings; use GD GD::Image->trueColor(1); my $im = new GD::Image(100, 100); my $clear = $im->colorAllocateAlpha(255, 255, 255, 127); my $black = $im->colorAllocateAlpha(0, 0, 0, 0); $im->alphaBlending(0); $im->filledRectangle(0, 0, 100, 100, $clear); $im->alphaBlending(1); $im->stringFT($black, "a-ttf-font.ttf", 12, 0, 20, 20, "x"); binmode STDOUT; print $im->png;

感谢您的指导。

It seems like a trivial problem, but nothing I've tried will make the background transparent.

use strict; use warnings; use GD GD::Image->trueColor(1); my $im = new GD::Image(100, 100); my $clear = $im->colorAllocateAlpha(255, 255, 255, 127); my $black = $im->colorAllocateAlpha(0, 0, 0, 0); $im->alphaBlending(0); $im->filledRectangle(0, 0, 100, 100, $clear); $im->alphaBlending(1); $im->stringFT($black, "a-ttf-font.ttf", 12, 0, 20, 20, "x"); binmode STDOUT; print $im->png;

Thanks for any guidance.

最满意答案

你在使用$im->saveAlpha(1)吗？ 否则，alpha信息仅在构建图像时有用。 保存的图像不会透明。

一个快速而肮脏的方法，可能不适合您的目的，是忘记alpha通道并使用GD::Image::transparent方法。

Are you using $im->saveAlpha(1)? Otherwise the alpha information is only useful in constructing the image. The saved image won't be transparent.

A quick and dirty method, which might not be good enough for your purposes, is to forget about the alpha channel and use the GD::Image::transparent method.