2D screenpace zooming

Question

我需要在perl上繪製2D圖像到大小爲1024x768的圖像;行的座標是unix時間戳，如x1 = 1365693813 y1 =（某個虛擬中心）x2 = 1365793815 y2 =（某個虛擬中心）。什麼公式可以將真實生活中的圖像縮放到圖像空間中？

Answer 1

假設($x1,$y1)和($x2,$y2)定義「視圖窗口」你的左下角和右上角的角落，你有一個點要繪製($x3,$y3)其中$x1 <= $x3 <= $x2和$y1 <= $y3 <= $y2。另外假設您正在標準圖像空間中（0,0）是圖像的左上角。你可以找到($xp, $yp)爲像素座標，以這樣的圖像繪製：

# View window 
my ($x1,$y1) = (1365693813, 100); 
my ($x2,$y2) = (1365693815, 200); 
my ($vw ,$vh) = ($x2 - $1, $y2 - $y1); 

# Image width/height 
my ($imgw,$imgh) = (1024, 768); 

# Point to plot in original co-ordinates 
my ($x3,$y3) = (1365693814, 150); 

# Calculate point to plot in image co-ordinates 
my $xp = int(($imgw * ($x3 - $x1)/$vw) + 0.5); 
my $yp = int(($imgh * (1.0 - ($y3 - $y1)/$vh)) + 0.5); 

# Now plot ($xp, $yp), provided it is inside the graphic!