Talk about PHP drawing (3)_PHP tutorial-PHP Tutorial-php.cn

Talk about PHP drawing (3)_PHP tutorial

WBOY

Release： 2016-07-13 17:35:42

Original

742 people have browsed it

上次说到用GD作各种几何图形，以及填充颜色。其中故意把这样一个较复杂的情况
留到后面，这就是任意多边形和任意多边形的填充颜色。

Header("Content-type: image/png");
$im = ImageCreate (200, 100);
$col_blk = ImageColorAllocate($im, 0,0,0);
$col_grn = ImageColorAllocate($im, 0,255,0);

$parray = array(40,10,60,10,70,20,60,50,40,50,30,20);
// 定义一个数组，12个成员是6个点的横纵坐标。
ImagePolygon($im,$parray,6,$col_grn);
// 这就是绘制任意多边形的函数，$parray是刚才定义的数组，
// 6表示六个点。注意六个点连成的是六边形。
// 不必人为地为了闭合图形而在最后增加一个与第一点相同的点。

ImagePNG($im);
ImageDestroy($im);
?>

你应该已经想到了，任意多边形填充颜色的函数：

Header("Content-type: image/png");
$im = ImageCreate (200, 100);
$col_blk = ImageColorAllocate($im, 0,0,0);
$col_orn = ImageColorAllocate($im, 255,192,0);
$col_yel = ImageColorAllocate($im, 255,255,0);
$col_red = ImageColorAllocate($im, 255,0,0);
$col_grn = ImageColorAllocate($im, 0,255,0);
$col_blu = ImageColorAllocate($im, 0,0,255);

$parray = array(40,10,60,10,70,20,60,50,40,50,30,20);
ImageFilledPolygon($im,$parray,6,$col_grn);

ImagePNG($im);
ImageDestroy($im);
?>

嗯。下面我们可以在图象上写字了。不过，先别高兴，要想写汉字还得费一些麻烦。
这个以后再逐渐解释。先看看怎么简单地写西文字符吧。

Header("Content-type: image/png");
$im = ImageCreate (200, 250);
$col_blk = ImageColorAllocate($im, 0,0,0);
$col_orn = ImageColorAllocate($im, 255,192,0);

$str="This is a test.";
ImageString($im,1,10,10,$str,$col_orn);
ImageString($im,2,10,30,$str,$col_orn);
ImageString($im,3,10,60,$str,$col_orn);
ImageString($im,4,10,100,$str,$col_orn);
ImageString($im,5,10,150,$str,$col_orn);
// 这里连续五次调用ImageString，在不同位置，
// 分别用从小到大的字型输出了字符串 $str。
// ImageString 函数只支持五种字型(1~5)

ImagePNG($im);
ImageDestroy($im);
?>

再看：

//Header("Content-type: image/png");
$im = ImageCreate (200, 250);
$col_blk = ImageColorAllocate($im, 0,0,0);
$col_orn = ImageColorAllocate($im, 255,192,0);

$str="This is a test.";
ImageStringUp($im,1,10,180,$str,$col_orn);
ImageStringUp($im,2,20,180,$str,$col_orn);
ImageStringUp($im,3,40,180,$str,$col_orn);
ImageStringUp($im,4,70,180,$str,$col_orn);
ImageStringUp($im,5,110,180,$str,$col_orn);
// 函数名换成了 ImageStringUp，用法不变。
// 是输出竖排的文字。

ImagePNG($im);
ImageDestroy($im);
?>

在使用输出字符的函数同时，如果能知道不同字型的字在图象里要占用的宽度、高度，
对于安排输出字符的位置将是多么方便的啊！PHP提供给我们了：ImageFontWidth()和
ImageFontHeight()，其参数很简单，只有一个：即字型的编号。例如ImageFontWidth(5)
就是取得5号字每个字符的宽度，ImageFontHeight(3)就是取得3号字每个字符的高度。这么
简单，就不举例了，等一下在后面的代码中还有用到。

跟输出字符串类似，ImageChar和ImageCharUp输出单个字符，用途比较少，甚至可以
不用——无论字符还是字符串，都用ImageString和ImageStringUp就可以了嘛！

下面，我就利用我做过的绘制股票K线分析图的其中一部分代码，把前面讲到的内容系统
地应用一下。因为其中涉及数据库，不能把原始代码拿过来给大家拿回去测试。只能构造一些
数据，模拟从数据库里取得的股市行情。鉴于这里懂股票K线的人可能不多，大家可能不知道K线
图应该怎么画法。然而，我也不能在这里讲K线具体是怎么回事，只是介绍这样一系列方法。等画
好以后，你肯定可以看出，以前确实见过这样的图。

Header("Content-type: image/png");

$im = ImageCreate(640,260);
$bkground = ImageColorAllocate($im,255,255,255);
$data = ImageColorAllocate($im,0,0,0);
$gird = ImageColorAllocate ($im,200,200,160);
$upline = ImageColorAllocate($im,255,0,0);
$dnline = ImageColorAllocate($im,0,175,175);
$d5line = ImageColorAllocate($im, 255,127,0);
$d20line = ImageColorAllocate($im,0,0,127);
$d10line = ImageColorAllocate($im,255,0,255);
// First define the methods used to draw various objects color.

for($i=20;$i<=220;$i+=25)
ImageLine($im, 60, $i, 560, $i, $gird);
for($j =60;$j<=560;$j+=25)
ImageLine($im, $j, 20, $j, 220, $gird);
// Calculate the position and grid width in advance, use The for loop draws lines, which saves a lot of trouble.

$zzg=10.55;
$zzd=7.63;
$lzg=10350;
// Hypothetical stock market data,
// $zzg is the highest value during the period that needs to be analyzed The price is assumed to be 10.55 yuan.
// $zzd is the lowest price during the period that needs to be analyzed, assuming it is 7.63 yuan.
// $lzg is the highest trading volume during the period that needs to be analyzed, assuming it is 10350 lots.
// This is important data for calculating the "scale" of the coordinate grid.
$bl=$zzg-$zzd;
// The difference between the highest price and the lowest price. According to the ratio between it and the total height of the grid,
// can get an actual price position in the grid.

for($i=1;$i<=7;$i++)
{
$y=$i*25-10;
// Calculate the label scale based on the position of the grid line the appropriate height (ordinate).
$str=Number_Format($zzg-($i-1)/6*$bl,2,".",",");
// Calculate the price and format corresponding to each tick mark ize the string.
$x=55-ImageFontWidth(2)*StrLen($str);
// Calculate the appropriate abscissa based on the width that this string will occupy.
ImageString($im, 2,$x, $y,$str, $data);
// Write this string.
}

$str=Number_Format($lzg,0,".",",");
ImageString($im,2,564,164,$str,$data);
$str=Number_Format($lzg/ 2,0,".",",");
ImageString($im,2,564,189,$str,$data);
// Since there are only two scales for writing volume, it is not easy to write it in a loop. It's a good deal.
// If the number is relatively large, looping should also be used.

// Since a K-line chart requires drawing countless small K-line bars, so drawing a small K-line bar is written as a function
function kline($img,$kp,$zg, $zd,$sp,$cjl,$ii)
// Parameters: $img image; $kp $zg $zd $sp is the opening, highest, lowest, closing price;
// $cjl trading volume ; $ii counter, indicating the serial number of the K-line bar.
{
global $bl,$zzd,$lzg;
// Declare the three variables $bl, $zzd, $lzg used in this function as global variables.
$h=150; // The height of the K-line column area is 150.
$hh=200; //The total height of the K-line column area and the volume column area is 200.

if($sp<$kp)
$linecolor = ImageColorAllocate($img,0,175,175);
// If the closing price is lower than the opening, it is a negative line, use cyan
else
$linecolor = ImageColorAllocate($img,255,0,0);
// Otherwise, it is a positive line, use red.

$x=58+$ii*4;
// Calculate the abscissa based on the K-line column number.
$y1=20+$h-($kp-$zzd)/$bl*$h;
// Calculate the corresponding ordinate based on the opening price.
$y2=20+$h-($sp-$zzd)/$bl*$h;
// Calculate the corresponding ordinate based on the closing price.
$y3=20+$h-($zg-$zzd)/$bl*$h;
// Calculate the corresponding ordinate based on the highest price.
$y4=20+$h-($zd-$zzd)/$bl*$h;
// Calculate the corresponding ordinate based on the lowest price.
$y5=20+$hh-$cjl/$lzg*($hh-$h);
// Calculate the corresponding ordinate based on the trading volume.

if($y1<=$y2) ImageFilledRectangle($img,$x-1,$y1,$x+1,$y2,$linecolor);
else ImageFilledRectangle($img,$x-1 ,$y2,$x+1,$y1,$linecolor);
// The abscissa decreases from 1 to increases by 1, and the span is 3. That is, draw a small filled rectangle with a width of 3.
// The height and vertical coordinate are determined by the opening and closing prices.
// After testing, it was found that this function must write the coordinates of the upper left point before the coordinates of the lower right point,
// instead of automatically determining which of the two points is the upper left or the lower right.

ImageFilledRectangle($img,$x-1,$y5,$x+1,220,$linecolor);
// Draw the volume cylinder based on the trading volume.
ImageLine($img,$x,$y3,$x,$y4,$linecolor);
// Draw upper and lower shadow lines based on the highest price and lowest price.