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PHP 圖表生成庫 Libchart 完整使用指南：柱狀、折線、餅圖與中文亂碼解決方案

編輯：PHP 相關知識

前言

Libchart 是純 PHP 實現的圖表生成庫，無需外部擴展即可輸出 PNG 格式的柱狀圖、折線圖、餅圖與橫向柱狀圖。本文將示範如何封裝通用繪圖類、解決中文亂碼（標題、軸標籤）、字體替換與實戰調用全流程。

一、快速上手：封裝通用繪圖類

<?php
require_once 'libchart/classes/libchart.php';

class ChartRenderer {
    private $chart;
    private int $style; // 1:垂直柱 2:折線 3:餅圖 4:橫向柱

    public function __construct(int $style = 1, int $width = 500, int $height = 250) {
        $this->style = $style;
        switch ($style) {
            case 1: $this->chart = new VerticalBarChart($width, $height); break;
            case 2: $this->chart = new LineChart($width, $height); break;
            case 3: $this->chart = new PieChart($width, $height); break;
            default: $this->chart = new HorizontalBarChart($width, $height);
        }
    }

    public function render(object $dataObj): void {
        $dataSet = null;
        $this->chart->setTitle($dataObj->title);

        switch ($this->style) {
            case 1: // 垂直柱狀圖
            case 4: // 橫向柱狀圖
                $dataSet = new XYDataSet();
                foreach ($dataObj->dataArray as $key => $val) {
                    $dataSet->addPoint(new Point($key, $val));
                }
                break;
            case 2: // 折線圖（支援多數據系列）
                $dataSet = new XYSeriesDataSet();
                $i = 0;
                foreach ($dataObj->dataArray as $seriesName => $seriesData) {
                    $serie = new XYDataSet();
                    foreach ($seriesData as $k => $v) {
                        $serie->addPoint(new Point($k, $v));
                    }
                    $dataSet->addSerie($seriesName, $serie);
                    $i++;
                }
                break;
            case 3: // 餅圖
                $dataSet = new XYDataSet();
                foreach ($dataObj->dataArray as $key => $val) {
                    $dataSet->addPoint(new Point("{$key} ({$val})", $val));
                }
                break;
        }

        $this->chart->setDataSet($dataSet);
        $this->chart->render();
    }
}

// 使用範例
$data = new stdClass();
$data->title = "年度銷售統計";
$data->dataArray = [
    "2020" => 120, "2021" => 150, "2022" => 180, "2023" => 210
];

$renderer = new ChartRenderer(1); // 垂直柱狀圖
$renderer->render($data);

二、中文亂碼完整解決方案

Libchart 內建字體不支援中文，需三步驟修正：

1. 數據與標題編碼轉換（即時方案）

$str = '二月';
$str = mb_convert_encoding($str, "HTML-ENTITIES", "UTF-8");
$dataSet->addPoint(new Point($str, 120));

$chart->setTitle(mb_convert_encoding("統計圖", "HTML-ENTITIES", "UTF-8"));

2. 修改 Chart.php 強制標題編碼（永久方案）

檔案：libchart/classes/view/chart/Chart.php

public function setTitle($title) {
    $title = mb_convert_encoding($title, "HTML-ENTITIES", "UTF-8");
    $this->plot->setTitle($title);
}

3. 替換中文字體檔（徹底解決軸標籤亂碼）

檔案：libchart/classes/view/text.php

public function __construct() {
    $baseDir = dirname(__FILE__) . "/../../../";
    // 下載中文字體（如思源黑體、微軟正黑體）放入 fonts 目錄
    $this->fontCondensed = $baseDir . "fonts/SourceHanSansTC-Regular.otf";
    $this->fontCondensedBold = $baseDir . "fonts/SourceHanSansTC-Bold.otf";
}

注意：字體檔需為 TTF/OTF 格式，確保 Web 伺服器可讀取權限。

三、實戰範例：多系列折線圖

$dataObj = new stdClass();
$dataObj->title = "雙產品銷售趨勢對比";
$dataObj->dataArray = [
    "產品A" => ["2021" => 100, "2022" => 150, "2023" => 200],
    "產品B" => ["2021" => 80,  "2022" => 120, "2023" => 180],
];

$renderer = new ChartRenderer(2, 600, 300); // 折線圖
$renderer->render($dataObj);