嗯，这是我的目标。使用鼠标左键滚动图像，鼠标右键选择缩放矩形，双击恢复全缩放。
我目前很累，到目前为止发现它与我加载图像或显示图像的方式无关，而是与它的绘画方式有关。无论窗体或源图像的形状如何，屏幕上的图像始终填充控件的客户区，因此不可能保留纵横比。我不知道如何改变这个或保持纵横比。因此给了我一张干净漂亮的照片。
我正在为我的 ZImage 单元发布整个代码虽然我认为问题出在 Zimage.paint 或 Zimage.mouseup 但想如果你需要在其中一个函数中查看一个函数，将它全部发布会有所帮助。
unit ZImage;
interface
uses
Windows, Messages, SysUtils,jpeg, Classes, Graphics, Controls, Forms, Dialogs,
ExtCtrls;
type
TZImage = class(TGraphicControl)
private
FBitmap : Tbitmap;
PicRect : TRect;
ShowRect : TRect;
FShowBorder : boolean;
FBorderWidth : integer;
FForceRepaint : boolean;
FMouse : (mNone, mDrag, mZoom);
FProportional : boolean;
FDblClkEnable : boolean;
FLeft :integer;
FRight :integer;
FTop :integer;
FBottom :integer;
startx, starty,
oldx, oldy : integer;
procedure SetShowBorder(s:boolean);
procedure SetBitmap(b:TBitmap);
procedure SetBorderWidth(w:integer);
procedure SetProportional(b:boolean);
protected
procedure Paint; override;
procedure MouseDown(Button: TMouseButton; Shift: TShiftState;
X, Y: Integer); override;
procedure MouseMove(Shift: TShiftState; X, Y: Integer); override;
procedure MouseUp(Button: TMouseButton; Shift: TShiftState;
X, Y: Integer); override;
public
constructor Create(AOwner:TComponent); override;
destructor Destroy; override;
procedure DblClick; override;
published
procedure zoom(Endleft,EndRight,EndTop,EndBottom:integer);
property ValueLeft : integer read FLeft write FLeft;
property ValueRight : Integer read FRight write FRight;
Property ValueTop : Integer read FTop write FTop;
Property ValueBottom : Integer read FBottom write FBottom;
property ShowBorder : boolean
read FShowBorder
write SetShowBorder default true;
property KeepAspect : boolean
read FProportional
write SetProportional default true;
property Bitmap : TBitmap
read FBitmap
write Setbitmap;
property BorderWidth : integer
read FBorderWidth
write SetBorderWidth default 7;
property ForceRepaint : boolean
read FForceRepaint
write FForceRepaint default true;
property DblClkEnable : boolean
read FDblClkEnable
write FDblClkEnable default False;
property Align;
property Width;
property Height;
property Top;
property Left;
property Visible;
property Hint;
property ShowHint;
end;
procedure Register;
implementation
//This is the basic create options.
constructor TZImage.Create(AOwner:TComponent);
begin
inherited;
FShowBorder:=True;
FBorderWidth:=7;
FMouse:=mNone;
FForceRepaint:=true; //was true
FDblClkEnable:=False;
FProportional:=true; //was true
Width:=100; Height:=100;
FBitmap:=Tbitmap.Create;
FBitmap.Width:=width;
FBitmap.height:=Height;
ControlStyle:=ControlStyle+[csOpaque];
autosize:= false;
//Scaled:=false;
end;
//basic destroy frees the FBitmap
destructor TZImage.Destroy;
begin
FBitmap.Free;
inherited;
end;
//This was a custom zoom i was using to give the automated zoom effect
procedure TZimage.zoom(Endleft,EndRight,EndTop,EndBottom:integer);
begin
while ((Endbottom <> picrect.bottom) or (Endtop <> picrect.top)) or ((endleft <> picrect.left) or (endright <> picrect.right)) do
begin
if picrect.left > endleft then
picrect.left := picrect.left -1;
if picrect.left < endleft then //starting
picrect.left := picrect.left +1;
if picrect.right > endright then //starting
picrect.right := picrect.right -1;
if picrect.right < endright then
picrect.right := picrect.right +1;
if picrect.top > endtop then
picrect.top := picrect.top -1;
if picrect.top < endtop then //starting
picrect.top := picrect.top +1;
if picrect.bottom > endbottom then //starting
picrect.bottom := picrect.bottom -1;
if picrect.bottom < endbottom then
picrect.bottom := picrect.bottom +1;
self.refresh;
end;
end;
//this is the custom paint I know if i put
//Canvas.Draw(0,0,FBitmap); as the methond it displays
//perfect but the zoom option is gone of course and
//i need the Zoom.
procedure TZImage.Paint;
var buf:TBitmap;
coef,asps,aspp:Double;
sz,a : integer;
begin
buf:=TBitmap.Create;
buf.Width:=Width;
buf.Height:=Height;
if not FShowBorder
then ShowRect:=ClientRect
else ShowRect:=Rect(ClientRect.Left,ClientRect.Top,
ClientRect.Right-FBorderWidth,
ClientRect.Bottom-FBorderWidth);
ShowRect:=ClientRect;
with PicRect do begin
if Right=0 then Right:=FBitmap.Width;
if Bottom=0 then Bottom:=FBitmap.Height;
end;
buf.Canvas.CopyMode:=cmSrcCopy;
buf.Canvas.CopyRect(ShowRect,FBitmap.Canvas,PicRect);
Canvas.CopyMode:=cmSrcCopy;
Canvas.Draw(0,0,buf);
buf.Free;
end;
procedure TZImage.MouseDown(Button: TMouseButton; Shift: TShiftState;
X, Y: Integer);
begin
// if mbLeft<>Button then Exit;
if not PtInRect(ShowRect,Point(X,Y)) and
not PtInRect(Rect(ShowRect.Right,ShowRect.Bottom,
Width,Height),Point(X,Y)) then Exit;
if PtInRect(Rect(ShowRect.Right,ShowRect.Bottom,
Width,Height),Point(X,Y)) then begin
DblClick;
Exit;
end;
//here click is in the picture area only
startx:=x; oldx:=x;
starty:=y; oldy:=y;
if mbRight=Button then begin
MouseCapture:=True;
FMouse:=mZoom;
Canvas.Pen.Mode:=pmNot;
end else begin
FMouse:=mDrag;
Screen.Cursor:=crHandPoint;
end;
end;
function Min(a,b:integer):integer;
begin
if a<b then Result:=a else Result:=b;
end;
function Max(a,b:integer):integer;
begin
if a<b then Result:=b else Result:=a;
end;
procedure TZImage.MouseMove(Shift: TShiftState; X, Y: Integer);
var d,s:integer;
coef:Double;
begin
if FMouse=mNone then Exit;
if FMouse=mZoom then begin
Canvas.DrawFocusRect(Rect(Min(startx,oldx),Min(starty,oldy),Max(startx,oldx),Max(starty,oldy)));
oldx:=x; oldy:=y;
Canvas.DrawFocusRect(Rect(Min(startx,oldx),Min(starty,oldy),Max(startx,oldx),Max(starty,oldy)));
end;
if FMouse=mDrag then begin
//horizontal movement
coef:=(PicRect.Right-PicRect.Left)/(ShowRect.Right-ShowRect.Left);
d:=Round(coef*(x-oldx));
s:=PicRect.Right-PicRect.Left;
if d>0 then begin
if PicRect.Left>=d then begin
PicRect.Left:=PicRect.Left-d;
PicRect.Right:=PicRect.Right-d;
end else begin
PicRect.Left:=0;
PicRect.Right:=PicRect.Left+s;
end;
end;
if d<0 then begin
if PicRect.Right<FBitmap.Width+d then begin
PicRect.Left:=PicRect.Left-d;
PicRect.Right:=PicRect.Right-d;
end else begin
PicRect.Right:=FBitmap.Width;
PicRect.Left:=PicRect.Right-s;
end;
end;
//vertical movement
coef:=(PicRect.Bottom-PicRect.Top)/(ShowRect.Bottom-ShowRect.Top);
d:=Round(coef*(y-oldy));
s:=PicRect.Bottom-PicRect.Top;
if d>0 then begin
if PicRect.Top>=d then begin
PicRect.Top:=PicRect.Top-d;
PicRect.Bottom:=PicRect.Bottom-d;
end else begin
PicRect.Top:=0;
PicRect.Bottom:=PicRect.Top+s;
end;
end;
{There was a bug in the fragment below. Thanks to all, who reported this bug to me}
if d<0 then begin
if PicRect.Bottom<FBitmap.Height+d then begin
PicRect.Top:=PicRect.Top-d;
PicRect.Bottom:=PicRect.Bottom-d;
end else begin
PicRect.Bottom:=FBitmap.Height;
PicRect.Top:=PicRect.Bottom-s;
end;
end;
oldx:=x; oldy:=y;
if FForceRepaint then Repaint
else Invalidate;
end;
end;
procedure TZImage.MouseUp(Button: TMouseButton; Shift: TShiftState;
X, Y: Integer);
var coef:Double;
t:integer;
left,right,top,bottom : integer;
begin
if FMouse=mNone then Exit;
if x>ShowRect.Right then x:=ShowRect.Right;
if y>ShowRect.Bottom then y:=ShowRect.Bottom;
if FMouse=mZoom then begin //calculate new PicRect
t:=startx;
startx:=Min(startx,x);
x:=Max(t,x);
t:=starty;
starty:=Min(starty,y);
y:=Max(t,y);
FMouse:=mNone;
MouseCapture:=False;
//enable the following if you want to zoom-out by dragging in the opposite direction}
{ if Startx>x then begin
DblClick;
Exit;
end;}
if Abs(x-startx)<5 then Exit;
//showmessage('picrect Left='+inttostr(picrect.Left)+' right='+inttostr(picrect.Right)+' top='+inttostr(picrect.Top)+' bottom='+inttostr(picrect.Bottom));
//startx and start y is teh starting x/y of the selected area
//x and y is the ending x/y of the selected area
if (x - startx < y - starty) then
begin
while (x - startx < y - starty) do
begin
x := x + 100;
startx := startx - 100;
end;
end
else if (x - startx > y - starty) then
begin
while (x - startx > y - starty) do
begin
y := y + 100;
starty := starty - 100;
end;
end;
//picrect is the size of whole area
//PicRect.top and left are 0,0
//IFs were added in v.1.2 to avoid zero-divide
if (PicRect.Right=PicRect.Left)
then
coef := 100000
else
coef:=ShowRect.Right/(PicRect.Right-PicRect.Left); //if new screen coef= 1
left:=Round(PicRect.Left+startx/coef);
Right:=Left+Round((x-startx)/coef);
if (PicRect.Bottom=PicRect.Top)
then
coef := 100000
else
coef:=ShowRect.Bottom/(PicRect.Bottom-PicRect.Top);
Top:=Round(PicRect.Top+starty/coef);
Bottom:=Top+Round((y-starty)/coef);
//showmessage(inttostr(left)+' '+inttostr(Right)+' '+inttostr(top)+' '+inttostr(bottom));
zoom(left,right,top,bottom);
ValueLeft := left;
ValueRight := Right;
ValueTop := top;
ValueBottom := bottom;
end;
if FMouse=mDrag then begin
FMouse:=mNone;
Canvas.Pen.Mode:=pmCopy;
Screen.Cursor:=crDefault;
end;
Invalidate;
end;
procedure TZImage.DblClick;
begin
zoom(0,FBitMap.Width,0,FBitMap.Height);
ValueLeft := 0;
ValueRight := FBitMap.Width;
ValueTop := 0;
ValueBottom := FBitMap.Height;
//PicRect:=Rect(0,0,FBitmap.Width,FBitmap.Height);
Invalidate;
end;
procedure TZImage.SetBitmap(b:TBitmap);
begin
FBitmap.Assign(b);
PicRect:=Rect(0,0,b.Width, b.Height);
Invalidate;
end;
procedure TZImage.SetBorderWidth(w:integer);
begin
FBorderWidth:=w;
Invalidate;
end;
procedure TZImage.SetShowBorder(s:boolean);
begin
FShowBorder:=s;
Invalidate;
end;
procedure TZImage.SetProportional(b:boolean);
begin
FProportional:=b;
Invalidate;
end;
procedure Register;
begin
RegisterComponents('Custom', [TZImage]);
end;
end.
使用此代码，您可以注册组件 ZImage 并查看它如何运行.. 如果需要
