PHP利用GD庫畫圖和生成驗證碼圖片

PHP利用GD庫畫圖和生成驗證碼圖片

首先得確定php.ini設置有沒有打開GD擴展功能，測試如下

print_r(gd_info());

Array
(
    [GD Version] => bundled (2.0.34 compatible)
    [FreeType Support] => 1
    [FreeType Linkage] => with freetype
    [T1Lib Support] => 1
    [GIF Read Support] => 1
    [GIF Create Support] => 1
    [JPG Support] => 1
    [PNG Support] => 1
    [WBMP Support] => 1
    [XPM Support] => 
    [XBM Support] => 1
    [JIS-mapped Japanese Font Support] => 
)

GD畫圖一般步驟如下：

1.創建一張畫布資源

2.創建顏色畫筆

3.畫圖

4.保存圖片或輸出圖片

5.銷毀內存畫布資源

測試代碼如下：

注：GD庫強大的可以畫各種報表（如柱狀圖，餅狀圖等）、縮略圖、加水印圖和股票走勢圖