在TCanvas上绘制拉伸和旋转的图像
我试图在某些指定的点上在TImage画布上绘制一个旋转的位图，到目前为止，我尝试旋转位图，然后使用拉伸绘制，但我没有得到我想要的结果，场景就像这样
- 我通过鼠标点击在TImage画布上绘制4个点并获得它的角度，角度可以是0,45,90任何东西，类似于我附加的图像
- 现在我需要的是在这些点上绘制另一个旋转和拉伸的位图，我很难解决这个问题
此致
2 个答案:
答案 0 :(得分：1)
许多年前，当明星更亮，女孩更年轻时，我写了这个代码的原因不明。它与VCL兼容，但可以采用，以便在VCL / FMX中使用。从位图到目标DC的任意矩形绘制任意矩形是简单的类（因此它可以是位图或其他东西）。它可以用双线性插值绘制目标图片，然后结果看起来不像简单拉伸那么难看。也许这对某人有用。
unit uBMPUtils;
interface
uses
windows, graphics, math, sysutils;
type
PIntegers = ^TIntegers;
TIntegers = array[0..high(integer) div sizeof(integer) - 16] of integer;
TDrawLine = procedure( pixelSize : integer;
var src;
srcLineAdd : integer;
src_x1, src_y1, src_x2, src_y2 : integer;
var dst;
dstLen : integer) of object;
TDrawMode = (dmSimple, dmBilinear);
TBitmapDrawer = class
protected
tmp : TBitmap;
koefs : array[0..4096*4-1] of integer; // addr(Ux, Vy) = 4 * ( (trunc(Ux*16) << 6) + trunc(Vy*16) )
calculated : boolean;
DrawModeFlag : TDrawMode;
DrawLine : TDrawLine;
procedure precalculate; // precalculate koefs for fast bilinear interpolation
procedure drawLineSimple( pixelSize : integer;
var src;
srcLineAdd : integer;
src_x1, src_y1, src_x2, src_y2 : integer;
var dst;
dstLen : integer);
procedure drawLineBilinear( pixelSize : integer;
var src;
srcLineAdd : integer;
src_x1, src_y1, src_x2, src_y2 : integer;
var dst;
dstLen : integer);
procedure setDrawMode(m : TDrawMode);
public
constructor Create;
destructor Destroy; override;
procedure DrawTriangle(src : TBitmap; // source bitmap (pf24 or pf32!)
dst_dc : cardinal; // destination DC
dstRect : TRect; // limiting rect for output
A1, A2, A3, // arbitrary rectange at Src bitmap
B1, B2, B3 : TPoint); // arbitrary rectange at DST_DC device
procedure DrawRectangle(src : TBitmap; // source bitmap (pf24 or pf32!)
dst_dc : cardinal; // destination DC
dstRect : TRect; // limiting rect for output
A1, A2, A3, A4, // arbitrary rectange at Src bitmap
B1, B2, B3, B4 : TPoint); // arbitrary rectange at DST_DC device
property DrawMode: TDrawMode read DrawModeFlag write setDrawMode; // Default: dmBilinear
end;
implementation
function HorAtLine(var x : integer; y, x1,y1,x2,y2 : integer):boolean;
begin
if y1 = y2 then result := false else
begin
result := (y >= y1) and (y <= y2) or (y >= y2) and (y <= y1);
if result then x := x1 + (x2 - x1) * (y - y1) div (y2 - y1);
end;
end;
procedure LineProportion(var src_x, src_y : integer;
src_x1, src_y1, src_x2, src_y2 : integer;
dst_x, dst_y : integer;
dst_x1, dst_y1, dst_x2, dst_y2 : integer);
begin
if abs(dst_x2 - dst_x1) > abs(dst_y2 - dst_y1) then begin // proportions form Y
src_x := src_x1 + (src_x2 - src_x1) * (dst_x - dst_x1) div (dst_x2 - dst_x1);
src_y := src_y1 + (src_y2 - src_y1) * (dst_x - dst_x1) div (dst_x2 - dst_x1);
end else begin
src_x := src_x1 + (src_x2 - src_x1) * (dst_y - dst_y1) div (dst_y2 - dst_y1);
src_y := src_y1 + (src_y2 - src_y1) * (dst_y - dst_y1) div (dst_y2 - dst_y1);
end;
end;
// ---------------------------------------------- TBitmapDrawer --------------------------------------------------------
procedure TBitmapDrawer.precalculate;
var
n, u, v : integer;
Uf, Vf, k1,k2,k3,k4 : double;
begin
calculated := true;
for V := 0 to 63 do
for U := 0 to 63 do
begin
Uf := U / 64;
Vf := V / 64;
k1 := (1 - Uf) * (1 - Vf);
k2 := Uf * (1 - Vf);
k3 := (1 - Uf) * Vf;
k4 := Uf * Vf;
n := ((U shl 6) + V) * 4;
koefs[n] := trunc(k1*65536);
koefs[n+1] := trunc(k2*65536);
koefs[n+2] := trunc(k3*65536);
koefs[n+3] := trunc(k4*65536);
end;
end;
constructor TBitmapDrawer.create;
begin
inherited create;
tmp := TBitmap.create;
tmp.Height := 1;
drawMode := dmBilinear;
precalculate;
end;
destructor TBitmapDrawer.Destroy;
begin
FreeandNil(tmp);
inherited;
end;
procedure TBitmapDrawer.DrawRectangle(src : TBitmap;
dst_dc : cardinal;
dstRect : TRect;
A1, A2, A3, A4,
B1, B2, B3, B4 : TPoint);
begin
DrawTriangle(src, dst_dc, dstRect, A1, A2, A3, B1, B2, B3);
DrawTriangle(src, dst_dc, dstRect, A1, A3, A4, B1, B3, B4);
end;
procedure TBitmapDrawer.DrawTriangle(src : TBitmap;
dst_dc : cardinal;
dstRect : TRect;
A1, A2, A3,
B1, B2, B3 : TPoint);
var
pixelSize, srcAdd, left_x, left_y, right_x, right_y: integer;
minx, maxx, x, y, top, bottom : integer;
pb : pointer;
begin
if src.height > 1 then srcAdd := integer(PAnsiChar(src.scanline[1]) - PAnsiChar(src.scanline[0])) else srcAdd := 0;
top := min(min(b1.y, b2.y), b3.y);
bottom := max(max(b1.y, b2.y), b3.y);
if (top > dstRect.Bottom) or (bottom < dstRect.Top) then exit;
if top < dstRect.Top then top := dstRect.Top;
if bottom > dstRect.Bottom then bottom := dstRect.Bottom;
case src.pixelFormat of
pf24bit : pixelsize := 3;
pf32bit : pixelsize := 4;
else raise exception.create('Error');
end;
if tmp.PixelFormat <> src.PixelFormat then tmp.PixelFormat := src.PixelFormat;
y := max(max(b1.X, b2.x), b3.x) - min(min(b1.X, b2.x), b3.x) + 1;
if (tmp.Width < y) then tmp.Width := y;
pb := tmp.scanline[0];
for y := top to bottom do // Y at destination picture
begin
minx := high(integer);
maxx := low(integer);
if HorAtLine(x,y, b1.X, b1.Y, b2.x, b2.Y) then
begin
if x < minx then begin
minx := x;
LineProportion(left_x, left_y, a1.X, a1.Y, a2.x, a2.Y, x,y, b1.X, b1.Y, b2.X, b2.Y);
end;
if x > maxx then begin
LineProportion(right_x, right_y, a1.X, a1.Y, a2.x, a2.Y, x,y, b1.X, b1.Y, b2.X, b2.Y);
maxx := x;
end;
end;
if HorAtLine(x,y, b2.X, b2.Y, b3.x, b3.Y) then
begin
if x < minx then begin
minx := x;
LineProportion(left_x, left_y, a2.X, a2.Y, a3.x, a3.Y, x,y, b2.X, b2.Y, b3.X, b3.Y);
end;
if x > maxx then begin
LineProportion(right_x, right_y, a2.X, a2.Y, a3.x, a3.Y, x,y, b2.X, b2.Y, b3.X, b3.Y);
maxx := x;
end;
end;
if HorAtLine(x,y, b3.X, b3.Y, b1.x, b1.Y) then
begin
if x < minx then begin
minx := x;
LineProportion(left_x, left_y, a3.X, a3.Y, a1.x, a1.Y, x,y, b3.X, b3.Y, b1.X, b1.Y);
end;
if x > maxx then begin
LineProportion(right_x, right_y, a3.X, a3.Y, a1.x, a1.Y, x,y, b3.X, b3.Y, b1.X, b1.Y);
maxx := x;
end;
end;
if minx > maxx then continue;
// destination line (minx, y) - (maxx, y) - now we can find it at source picture
drawLine(pixelSize, src.ScanLine[0]^, srcAdd, left_x, left_y, right_x, right_y, pb^, maxx - minx + 1);
bitblt(dst_dc, minx, y, maxx-minx+1, 1, tmp.Canvas.Handle, 0,0, srccopy);
end;
end;
procedure TBitmapDrawer.drawLineSimple( pixelSize : integer;
var src;
srcLineAdd : integer;
src_x1, src_y1, src_x2, src_y2 : integer;
var dst;
dstLen : integer);
var
dst_ptr : PAnsiChar;
i, px, py : integer;
begin
dst_ptr := @dst;
px := (src_x2 - src_x1) * 65536 div dstLen;
py := (src_y2 - src_y1) * 65536 div dstLen;
src_x1 := src_x1 * 65536;
src_y1 := src_y1 * 65536;
for i := 0 to dstLen - 1 do
begin
pinteger(dst_ptr)^ := pinteger( PAnsiChar(@src) +
((src_y1 + i * py) shr 16) * srcLineAdd +
((src_x1 + i * px) shr 16) * pixelSize
)^;
inc(dst_ptr, pixelSize);
end;
end;
procedure TBitmapDrawer.drawLineBilinear( pixelSize : integer;
var src;
srcLineAdd : integer;
src_x1, src_y1, src_x2, src_y2 : integer;
var dst;
dstLen : integer);
var
src_ptr, dst_ptr : PAnsiChar;
u,v,Uf,Vf : integer;
i : integer;
k : PIntegers;
c1,c2,c3,c4 : TColor;
begin
dst_ptr := @dst;
for i := 0 to dstLen - 1 do
begin
u := src_x1 + i * (src_x2 - src_x1) div dstLen;
v := src_y1 + i * (src_y2 - src_y1) div dstLen;
Uf := (src_x1 + i * (src_x2 - src_x1) * 64 div dstLen) and $3f;
Vf := (src_y1 + i * (src_y2 - src_y1) * 64 div dstLen) and $3f;
k := @koefs[4*((Uf shl 6) + Vf)];
src_ptr := PAnsiChar(@src) + v * srcLineAdd + u * pixelSize;
c1 := pinteger(src_ptr)^;
c2 := pinteger(src_ptr + 4)^;
c3 := pinteger(src_ptr + srcLineAdd)^;
c4 := pinteger(src_ptr + srcLineAdd + 4)^;
pinteger(dst_ptr)^ :=
( (c1 and $FF)*k[0] shr 16 +
(c2 and $FF)*k[1] shr 16 +
(c3 and $FF)*k[2] shr 16 +
(c4 and $FF)*k[3] shr 16 )
or
( ((c1 shr 8) and $FF)*k[0] shr 16 +
((c2 shr 8) and $FF)*k[1] shr 16 +
((c3 shr 8) and $FF)*k[2] shr 16 +
((c4 shr 8) and $FF)*k[3] shr 16 ) shl 8
or
( ((c1 shr 16) and $FF)*k[0] shr 16 +
((c2 shr 16) and $FF)*k[1] shr 16 +
((c3 shr 16) and $FF)*k[2] shr 16 +
((c4 shr 16) and $FF)*k[3] shr 16 ) shl 16
or $02000000;
inc(dst_ptr, pixelSize);
end;
end;
procedure TBitmapDrawer.setDrawMode(m: TDrawMode);
begin
drawModeFlag := m;
case drawModeFlag of
dmSimple : drawLine := drawLineSimple;
dmBilinear : drawLine := drawLineBilinear;
end;
end;
end.
答案 1 :(得分：0)
我终于使用Graphics32 http://graphics32.org/wiki/
中的投影变换方法获得了所需的输出
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