imagefilltoborder 和imagecopymerge 混合使用的實戰案例分析

gitbox 2025-09-18

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</span><span><span class="hljs-meta">?&gt;</span></span><span>

&lt;hr&gt;

</span><span><span class="hljs-comment"># imagefilltoborder 和 imagecopymerge 混合使用的實戰案例分析</span></span><span>

在 PHP 的圖像處理功能中，`imagefilltoborder` 和 `imagecopymerge` 是兩個非常實用的函數。它們各自功能明確，但當兩者結合使用時，可以實現一些更加靈活和高級的圖像處理效果。本文將通過一個實戰案例，詳細分析這兩個函數的混合使用方法。

</span><span><span class="hljs-comment">## 一、函數簡介</span></span><span>

</span><span><span class="hljs-number">1</span></span><span>. **imagefilltoborder**
   - 功能：從指定點開始填充顏色，直到遇到指定邊界顏色為止。
   - 常用場景：實現區域填充、複雜形狀的背景填充等。

   ```php
   </span><span><span class="hljs-title function_ invoke__">imagefilltoborder</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-variable">$x</span></span><span>, </span><span><span class="hljs-variable">$y</span></span><span>, </span><span><span class="hljs-variable">$border_color</span></span><span>, </span><span><span class="hljs-variable">$fill_color</span></span><span>);
</span></span>

參數說明：

$image ：目標圖像資源。
$x , $y ：起始填充點坐標。
$border_color ：邊界顏色，當遇到此顏色時停止填充。
$fill_color ：填充顏色。

imagecopymerge

功能：將一幅圖像合併到另一幅圖像上，並可以控制透明度。
常用場景：製作水印、疊加圖片等。

 <span><span><span class="hljs-title function_ invoke__">imagecopymerge</span></span><span>(</span><span><span class="hljs-variable">$dst_image</span></span><span>, </span><span><span class="hljs-variable">$src_image</span></span><span>, </span><span><span class="hljs-variable">$dst_x</span></span><span>, </span><span><span class="hljs-variable">$dst_y</span></span><span>, </span><span><span class="hljs-variable">$src_x</span></span><span>, </span><span><span class="hljs-variable">$src_y</span></span><span>, </span><span><span class="hljs-variable">$src_w</span></span><span>, </span><span><span class="hljs-variable">$src_h</span></span><span>, </span><span><span class="hljs-variable">$pct</span></span><span>);
</span></span>

參數說明：

$dst_image ：目標圖像資源。
$src_image ：源圖像資源。
$dst_x , $dst_y ：目標圖像上的起始坐標。
$src_x , $src_y ：源圖像上的起始坐標。
$src_w , $src_h ：源圖像的寬高。
$pct ：合併的透明度百分比。

二、實戰案例：製作漸變邊框圖

假設我們想在一張圖片上添加一個漸變色填充的邊框，並在邊框中疊加一個半透明的logo。我們可以先使用imagefilltoborder填充邊框，再用imagecopymerge添加logo。

步驟一：創建畫布和邊框

<span><span><span class="hljs-variable">$width</span></span><span> = </span><span><span class="hljs-number">400</span></span><span>;
</span><span><span class="hljs-variable">$height</span></span><span> = </span><span><span class="hljs-number">300</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">// 定義顏色</span></span><span>
</span><span><span class="hljs-variable">$white</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecolorallocate</span></span><span>(</span><span><span class="hljs-variable">$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-variable">$black</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecolorallocate</span></span><span>(</span><span><span class="hljs-variable">$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-variable">$red</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecolorallocate</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">255</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-number">0</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">$image</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-number">0</span></span><span>, </span><span><span class="hljs-variable">$white</span></span><span>);

</span><span><span class="hljs-comment">// 使用 imagefilltoborder 創建紅色邊框</span></span><span>
</span><span><span class="hljs-title function_ invoke__">imagefilltoborder</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-number">1</span></span><span>, </span><span><span class="hljs-number">1</span></span><span>, </span><span><span class="hljs-variable">$white</span></span><span>, </span><span><span class="hljs-variable">$red</span></span><span>);
</span></span>

步驟二：加載logo 並合併

<span><span><span class="hljs-variable">$logo</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagecreatefrompng</span></span><span>(</span><span><span class="hljs-string">'logo.png'</span></span><span>); </span><span><span class="hljs-comment">// 假設 logo 是 PNG 格式</span></span><span>
</span><span><span class="hljs-variable">$logo_width</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagesx</span></span><span>(</span><span><span class="hljs-variable">$logo</span></span><span>);
</span><span><span class="hljs-variable">$logo_height</span></span><span> = </span><span><span class="hljs-title function_ invoke__">imagesy</span></span><span>(</span><span><span class="hljs-variable">$logo</span></span><span>);

</span><span><span class="hljs-comment">// 將 logo 合併到右下角，透明度 50%</span></span><span>
</span><span><span class="hljs-title function_ invoke__">imagecopymerge</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>, </span><span><span class="hljs-variable">$logo</span></span><span>, </span><span><span class="hljs-variable">$width</span></span><span> - </span><span><span class="hljs-variable">$logo_width</span></span><span> - </span><span><span class="hljs-number">10</span></span><span>, </span><span><span class="hljs-variable">$height</span></span><span> - </span><span><span class="hljs-variable">$logo_height</span></span><span> - </span><span><span class="hljs-number">10</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">$logo_width</span></span><span>, </span><span><span class="hljs-variable">$logo_height</span></span><span>, </span><span><span class="hljs-number">50</span></span><span>);
</span></span>

步驟三：輸出圖像並釋放資源

<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">$image</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">imagedestroy</span></span><span>(</span><span><span class="hljs-variable">$image</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">imagedestroy</span></span><span>(</span><span><span class="hljs-variable">$logo</span></span><span>);
</span></span>

三、實戰分析

混合使用優勢
- imagefilltoborder可快速填充任意閉合區域的背景顏色，減少手動繪製邊框的複雜度。
- imagecopymerge可以在填充好的區域上疊加半透明元素，實現複雜圖層效果。
- 兩者結合，可靈活處理背景和裝飾層，實現視覺美化。
注意事項
- 邊界顏色必須正確，否則imagefilltoborder會超出預期範圍。
- imagecopymerge的透明度值要根據背景色和前景圖調整，避免出現過暗或顏色失真。
- PNG 圖像的透明背景處理時，需確保目標圖像支持alpha 通道，否則透明效果會丟失。

四、總結

通過本案例，可以看到imagefilltoborder與imagecopymerge的組合能夠實現複雜圖像處理效果。先用imagefilltoborder填充區域，再用imagecopymerge添加裝飾或logo，可以快速創建帶邊框、帶水印或疊加效果的圖像。掌握這兩個函數的配合使用技巧，對於PHP 圖像處理開發者來說是非常實用的技能。

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