php - 文本的自动字体大小(GD 通过 PHP)

Question

$im(GD 图像资源)上有一个 x*y 的空间供文本继续使用，我如何选择字体大小(或编写文本)使其不会溢出该区域？

Answer 1

我想你在寻找 imagettfbbox功能。

几年前，我将它用于为 Web 界面生成本地化按钮的脚本。如果文本不适合模板，我实际上调整了按钮的大小，以保持文本大小一致，但您可以尝试减小文本大小直到文本适合。

如果您有兴趣，我可以粘贴一些我的代码片段(或立即提供)。

[编辑] 好的，这是我的代码的一些摘录，总有一天我会清理它(使其独立于目标应用程序，提供示例)并将其作为一个整体公开。
我希望这些片段有意义。

// Bounding boxes: ImageTTFBBox, ImageTTFText:
// Bottom-Left: $bb[0], $bb[1]
// Bottom-Right: $bb[2], $bb[3]
// Top-Right: $bb[4]; $bb[5]
// Top-Left: $bb[6], $bb[7]
define('GDBB_TOP', 5);
define('GDBB_LEFT', 0);
define('GDBB_BOTTOM', 1);
define('GDBB_RIGHT', 2);

#[ In class constructor ]#
// Get size in pixels, must convert to points for GD2.
// Because GD2 assumes 96 pixels per inch and we use more "standard" 72.
$this->textSize *= 72/96;
$this->ComputeTextDimensions($this->textSize, FONT, $this->text);

#[ Remainder of the class (extract) ]
/**
 * Compute the dimensions of the text.
 */
function ComputeTextDimensions($textSize, $fontFile, $text)
{
    $this->textAreaWidth = $this->imageHSize - $this->marginL - $this->marginR;
    $this->textAreaHeight = $this->imageVSize - $this->marginT - $this->marginB;

    // Handle text on several lines
    $this->lines = explode(NEWLINE_CHAR, $text);
    $this->lineNb = count($this->lines);
    if ($this->lineNb == 1)
    {
        $bb = ImageTTFBBox($textSize, 0, $fontFile, $text);
        $this->textWidth[0] = $bb[GDBB_RIGHT] - $bb[GDBB_LEFT];
        $this->maxTextWidth = $this->textWidth[0];
        $this->textHeight[0] = $bb[GDBB_BOTTOM] - $bb[GDBB_TOP];
    }
    else
    {
        for ($i = 0; $i < $this->lineNb; $i++)
        {
            $bb = ImageTTFBBox($textSize, 0, $fontFile, $this->lines[$i]);
            $this->textWidth[$i] = $bb[GDBB_RIGHT] - $bb[GDBB_LEFT];
            $this->maxTextWidth = max($this->maxTextWidth, $this->textWidth[$i]);
            $this->textHeight[$i] = $bb[GDBB_BOTTOM] - $bb[GDBB_TOP];
        }
    }
    // Is the given text area width too small for asked text?
    if ($this->maxTextWidth > $this->textAreaWidth)
    {
        // Yes! Increase button size
        $this->textAreaWidth = $this->maxTextWidth;
        $this->imageHSize = $this->textAreaWidth + $this->marginL + $this->marginR;
    }
    // Now compute the text positions given the new (?) text area width
    if ($this->lineNb == 1)
    {
        $this->ComputeTextPosition(0, $textSize, $fontFile, $text, false);
    }
    else
    {
        for ($i = 0; $i < $this->lineNb; $i++)
        {
            $this->ComputeTextPosition($i, $textSize, $fontFile, $this->lines[$i], false);
        }
    }
}

/**
 * Compute xText and yText (text position) for the given text.
 */
function ComputeTextPosition($index, $textSize, $fontFile, $text, $centerAscDesc)
{
    switch ($this->textAlign)
    {
    case 'L':
        $this->xText[$index] = $this->marginL;
        break;
    case 'R':
        $this->xText[$index] = $this->marginL + 
                $this->textAreaWidth - $this->textWidth[$index];
        break;
    case 'C':
    default:
        $this->xText[$index] = $this->marginL + 
                ($this->textAreaWidth - $this->textWidth[$index]) / 2;
        break;
    }

    if ($centerAscDesc)
    {
        // Must compute the difference between baseline and bottom of BB.
        // I have to use a temporary image, as ImageTTFBBox doesn't use coordinates
        // providing offset from the baseline.
        $tmpBaseline = 5;
        // Image size isn't important here, GD2 still computes correct BB
        $tmpImage = ImageCreate(5, 5);
        $bbt = ImageTTFText($tmpImage, $this->textSize, 0, 0, $tmpBaseline,
                $this->color, $fontFile, $text);
        // Bottom to Baseline
        $baselinePos = $bbt[GDBB_BOTTOM] - $tmpBaseline;
        ImageDestroy($tmpImage);
        $this->yText[$index] = $this->marginT + $this->textAreaHeight -
                ($this->textAreaHeight - $this->textHeight) / 2 - $baselinePos + 0.5;
    }
    else
    {
        // Actually, we want to center the x-height, ie. to keep the baseline at same pos.
        // whatever the text is really, ie. independantly of ascenders and descenders.
        // This provide better looking buttons, as they are more consistent.
        $bbt = ImageTTFBBox($textSize, 0, $fontFile, "moxun");
        $tmpHeight = $bbt[GDBB_BOTTOM] - $bbt[GDBB_TOP];
        $this->yText[$index] = $this->marginT + $this->textAreaHeight -
                ($this->textAreaHeight - $tmpHeight) / 2 + 0.5;
    }
}

/**
 * Add the text to the button.
 */
function DrawText()
{
    for ($i = 0; $i < $this->lineNb; $i++)
    {
        // Increase slightly line height
        $yText = $this->yText[$i] + $this->textHeight[$i] * 1.1 * 
                ($i - ($this->lineNb - 1) / 2);
        ImageTTFText($this->image, $this->textSize, 0,
                $this->xText[$i], $yText, $this->color, FONT, $this->lines[$i]);
    }
}