怎樣結合imagestringup和imagecreatetruecolor創建豎直文本圖片？完整步驟解析

gitbox 2025-07-03

1.初始化圖像畫布

首先，我們需要創建一個空白的畫布，方便在其上繪製內容。 imagecreatetruecolor()函數是用來創建一個真彩色的畫布，它允許我們設置圖像的寬度和高度。

 <span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 設置圖片的寬度和高度</span></span><span>
</span><span><span class="hljs-variable">$width</span></span><span> = </span><span><span class="hljs-number">300</span></span><span>;
</span><span><span class="hljs-variable">$height</span></span><span> = </span><span><span class="hljs-number">100</span></span><span>;

</span><span><span class="hljs-comment">// 創建一個真彩色的畫布</span></span><span>
</span><span><span class="hljs-variable">$image</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecreatetruecolor</span></span><span>(</span><span><span class="hljs-variable">$width</span></span><span>, </span><span><span class="hljs-variable">$height</span></span><span>);
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

在這個步驟中，我們為圖片定義了一個寬300 像素，高100 像素的畫布。

2.分配顏色

我們可以使用imagecolorallocate()函數為圖像分配顏色。此函數返回的顏色可以用來繪製文本、背景等。

 <span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 分配顏色</span></span><span>
</span><span><span class="hljs-variable">$bgColor</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecolorallocate</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">255</span></span><span>, </span><span><span class="hljs-number">255</span></span><span>, </span><span><span class="hljs-number">255</span></span><span>); </span><span><span class="hljs-comment">// 白色背景</span></span><span>
</span><span><span class="hljs-variable">$textColor</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecolorallocate</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>); </span><span><span class="hljs-comment">// 黑色文本</span></span><span>
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

在這個示例中，我們為圖像設置了一個白色的背景顏色和黑色的文本顏色。

3.填充背景

接下來，我們使用imagefill()或imagefilltoborder()函數填充背景。這一操作可以確保畫布有一個統一的背景色。

 <span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 填充背景為白色</span></span><span>
</span><span><span class="hljs-title function_ invoke__">imagefill</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-variable">$bgColor</span></span><span>);
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

4.繪製豎直文本

這一步是關鍵，我們利用imagestringup()函數來繪製豎直的文本。 imagestringup()用於將文本沿著圖像的豎直方向繪製。它的參數如下：

$image : 要繪製的圖像資源
$font : 字體大小
$x : 文本的橫坐標
$y : 文本的縱坐標
$string : 要繪製的文本
$color : 字體顏色

<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 使用 imagestringup 繪製豎直文本</span></span><span>
</span><span><span class="hljs-title function_ invoke__">imagestringup</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">5</span></span><span>, </span><span><span class="hljs-number">50</span></span><span>, </span><span><span class="hljs-number">50</span></span><span>, </span><span><span class="hljs-string">"豎直文本"</span></span><span>, </span><span><span class="hljs-variable">$textColor</span></span><span>);
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

在這個例子中，我們將文本"豎直文本"繪製到畫布的坐標(50, 50)處，並且文本是豎直顯示的。

5.輸出圖像

完成繪製後，我們可以選擇將圖像輸出為文件或直接顯示在瀏覽器中。使用imagepng()或imagejpeg()等函數可以將圖像輸出為不同格式，或者使用header()函數將圖像直接輸出到瀏覽器。

 <span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 輸出到瀏覽器</span></span><span>
</span><span><span class="hljs-title function_ invoke__">header</span></span><span>(</span><span><span class="hljs-string">'Content-Type: image/png'</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">imagepng</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>);

</span><span><span class="hljs-comment">// 銷毀圖像資源</span></span><span>
</span><span><span class="hljs-title function_ invoke__">imagedestroy</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>);
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

這段代碼會將圖像直接輸出到瀏覽器，圖像格式為PNG。在輸出完畢後，調用imagedestroy()釋放內存。

6.完整代碼示例

將以上步驟組合起來，完整的代碼示例如下：

 <span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// 設置圖片的寬度和高度</span></span><span>
</span><span><span class="hljs-variable">$width</span></span><span> = </span><span><span class="hljs-number">300</span></span><span>;
</span><span><span class="hljs-variable">$height</span></span><span> = </span><span><span class="hljs-number">100</span></span><span>;

</span><span><span class="hljs-comment">// 創建一個真彩色的畫布</span></span><span>
</span><span><span class="hljs-variable">$image</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecreatetruecolor</span></span><span>(</span><span><span class="hljs-variable">$width</span></span><span>, </span><span><span class="hljs-variable">$height</span></span><span>);

</span><span><span class="hljs-comment">// 分配顏色</span></span><span>
</span><span><span class="hljs-variable">$bgColor</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecolorallocate</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">255</span></span><span>, </span><span><span class="hljs-number">255</span></span><span>, </span><span><span class="hljs-number">255</span></span><span>); </span><span><span class="hljs-comment">// 白色背景</span></span><span>
</span><span><span class="hljs-variable">$textColor</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecolorallocate</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>); </span><span><span class="hljs-comment">// 黑色文本</span></span><span>

</span><span><span class="hljs-comment">// 填充背景為白色</span></span><span>
</span><span><span class="hljs-title function_ invoke__">imagefill</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-variable">$bgColor</span></span><span>);

</span><span><span class="hljs-comment">// 使用 imagestringup 繪製豎直文本</span></span><span>
</span><span><span class="hljs-title function_ invoke__">imagestringup</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">5</span></span><span>, </span><span><span class="hljs-number">50</span></span><span>, </span><span><span class="hljs-number">50</span></span><span>, </span><span><span class="hljs-string">"豎直文本"</span></span><span>, </span><span><span class="hljs-variable">$textColor</span></span><span>);

</span><span><span class="hljs-comment">// 輸出圖像到瀏覽器</span></span><span>
</span><span><span class="hljs-title function_ invoke__">header</span></span><span>(</span><span><span class="hljs-string">'Content-Type: image/png'</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">imagepng</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>);

</span><span><span class="hljs-comment">// 銷毀圖像資源</span></span><span>
</span><span><span class="hljs-title function_ invoke__">imagedestroy</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>);
</span><span><span class="hljs-meta">?&gt;</span></span><span>
</span></span>

7.效果與總結

執行上述代碼後，我們將會看到一個包含豎直文本的圖片。在此過程中，我們使用了imagecreatetruecolor()創建畫布， imagecolorallocate()分配顏色， imagestringup()繪製豎直文本，最後通過imagepng()輸出圖像。

通過這幾步，你可以輕鬆地創建包含豎直文本的圖片，並將其應用於網頁、圖像處理等場景。希望本文的解析能夠幫助你更好地理解PHP 圖像處理的基本操作，特別是如何使用imagestringup()繪製豎直文本。