php生成高清縮略圖實例

php生成高清縮略圖的方法,較爲詳細的分析了php生成縮略圖時出現失真的解決方法,並給出了完整實例進行總結分析,需要的朋友可以參考下。

在使用php的函數生成縮略圖的`使用，縮略圖很多情況下都會失真，這個時候需要有一些對應的解決方法。

1.用imagecreatetruecolor和imageCopyreSampled函數分別取代imagecreate和imagecopyresized

2.給imagejpeg的第三個參數帶上100(例:imagejpeg($ni,$toFile,100))

　　下面是具體的函數

function CreateSmallImage( $OldImagePath, $NewImagePath, $NewWidth=154, $NewHeight=134)

{

// 取出原圖，獲得圖形信息getimagesize參數說明：0(寬),1(高),2(1gif/2jpg/3png),3(width="638" height="340")

$OldImageInfo = getimagesize($OldImagePath);

if ( $OldImageInfo[2] == 1 ) $OldImg = @imagecreatefromgif($OldImagePath);

elseif ( $OldImageInfo[2] == 2 ) $OldImg = @imagecreatefromjpeg($OldImagePath);

else $OldImg = @imagecreatefrompng($OldImagePath);

// 創建圖形,imagecreate參數說明：寬,高

$NewImg = imagecreatetruecolor( $NewWidth, $NewHeight );

//創建色彩,參數：圖形,red(0-255),green(0-255),blue(0-255)

$black = ImageColorAllocate( $NewImg, 0, 0, 0 ); //黑色

$white = ImageColorAllocate( $NewImg, 255, 255, 255 ); //白色

$red = ImageColorAllocate( $NewImg, 255, 0, 0 ); //紅色

$blue = ImageColorAllocate( $NewImg, 0, 0, 255 ); //藍色

$other = ImageColorAllocate( $NewImg, 0, 255, 0 );

//新圖形高寬處理

$WriteNewWidth = $NewHeight*($OldImageInfo[0] / $OldImageInfo[1]); //要寫入的高度

$WriteNewHeight = $NewWidth*($OldImageInfo[1] / $OldImageInfo[0]); //要寫入的寬度

//這樣處理圖片比例會失調，但可以填滿背景

if ($OldImageInfo[0] / $NewWidth > $org_info[1] / $NewHeight) {

$WriteNewWidth = $NewWidth;

$WriteNewHeight = $NewWidth / ($OldImageInfo[0] / $OldImageInfo[1]);

} else {

$WriteNewWidth = $NewHeight * ($OldImageInfo[0] / $OldImageInfo[1]);

$WriteNewHeight = $NewHeight;

}

//以$NewHeight爲基礎,如果新寬小於或等於$NewWidth,則成立

if ( $WriteNewWidth <= $NewWidth ) {

$WriteNewWidth = $WriteNewWidth; //用判斷後的大小

$WriteNewHeight = $NewHeight; //用規定的大小

$WriteX = floor( ($NewWidth-$WriteNewWidth) / 2 ); //在新圖片上寫入的X位置計算

$WriteY = 0;

} else {

$WriteNewWidth = $NewWidth; // 用規定的大小

$WriteNewHeight = $WriteNewHeight; //用判斷後的大小

$WriteX = 0;

$WriteY = floor( ($NewHeight-$WriteNewHeight) / 2 ); //在新圖片上寫入的X位置計算

}

//舊圖形縮小後,寫入到新圖形上(複製),imagecopyresized參數說明：新舊, 新xy舊xy, 新寬高舊寬高

@imageCopyreSampled( $NewImg, $OldImg, $WriteX, $WriteY, 0, 0, $WriteNewWidth, $WriteNewHeight, $OldImageInfo[0], $OldImageInfo[1] );

//保存文件

// @imagegif( $NewImg, $NewImagePath );

@imagejpeg($NewImg, $NewImagePath, 100);

//結束圖形

@imagedestroy($NewImg);

}

CreateSmallImage("./images/jiexie.jpg","./images/jiexie.small.jpg",200,300);

CreateSmallImage("./images/jiexie.jpg","./images/jiexie.middle.jpg",400,500);

希望本文所述對大家php程序設計有所幫助。