Add ability to set a background image. I import a png with libpng,

load it as a texture, and show it instead of a flat-color
background. Includes user interface to specify scale and
translation of image, but the rotation is always aligned to the
view.

[git-p4: depot-paths = "//depot/solvespace/": change = 2071]

draw.cpp

@@ -479,9 +479,58 @@ void GraphicsWindow::Paint(int w, int h) {
         ForceTextWindowShown();
     }
 
-    glClearDepth(1.0); 
     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
 
+    if(SS.bgImage.fromFile) {
+        // If a background image is loaded, then we draw it now as a texture.
+        // This handles the resizing for us nicely.
+        glBindTexture(GL_TEXTURE_2D, 10);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,     GL_CLAMP);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,     GL_CLAMP);
+        glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
+                     SS.bgImage.rw, SS.bgImage.rh,
+                     0,
+                     GL_RGB, GL_UNSIGNED_BYTE,
+                     SS.bgImage.fromFile);
+
+        double tw = ((double)SS.bgImage.w) / SS.bgImage.rw,
+               th = ((double)SS.bgImage.h) / SS.bgImage.rh;
+
+        double mmw = SS.bgImage.w / SS.bgImage.scale,
+               mmh = SS.bgImage.h / SS.bgImage.scale;
+
+        Vector origin = SS.bgImage.origin;
+        origin = origin.DotInToCsys(projRight, projUp, n);
+        // Place the depth of our origin at the point that corresponds to
+        // w = 1, so that it's unaffected by perspective.
+        origin.z = (offset.ScaledBy(-1)).Dot(n);
+        origin = origin.ScaleOutOfCsys(projRight, projUp, n);
+
+        glEnable(GL_TEXTURE_2D);
+        glBegin(GL_QUADS);
+            glTexCoord2d(0, 0);
+            glxVertex3v(origin);
+
+            glTexCoord2d(0, th);
+            glxVertex3v(origin.Plus(projUp.ScaledBy(mmh)));
+
+            glTexCoord2d(tw, th);
+            glxVertex3v(origin.Plus(projRight.ScaledBy(mmw).Plus(
+                                    projUp.   ScaledBy(mmh))));
+
+            glTexCoord2d(tw, 0);
+            glxVertex3v(origin.Plus(projRight.ScaledBy(mmw)));
+        glEnd();
+        glDisable(GL_TEXTURE_2D);
+    }
+
+    // Now clear the depth; so the background color and image are both at
+    // the very back of everything.
+    glClearDepth(1.0); 
+
     // Nasty case when we're reloading the imported files; could be that
     // we get an error, so a dialog pops up, and a message loop starts, and
     // we have to get called to paint ourselves. If the sketch is screwed

mouse.cpp

@@ -79,6 +79,13 @@ void GraphicsWindow::MouseMoved(double x, double y, bool leftDown,
     if(GraphicsEditControlIsVisible()) return;
     if(context.active) return;
 
+    if(!orig.mouseDown) {
+        // If someone drags the mouse into our window with the left button
+        // already depressed, then we don't have our starting point; so
+        // don't try.
+        leftDown = false;
+    }
+
     if(rightDown) {
         middleDown = true;
         shiftDown = !shiftDown;
@@ -703,6 +710,8 @@ bool GraphicsWindow::ConstrainPointByHovered(hEntity pt) {
 }
 
 void GraphicsWindow::MouseLeftDown(double mx, double my) {
+    orig.mouseDown = true;
+
     if(GraphicsEditControlIsVisible()) return;
     HideTextEditControl();
 
@@ -974,6 +983,8 @@ void GraphicsWindow::MouseLeftDown(double mx, double my) {
 }
 
 void GraphicsWindow::MouseLeftUp(double mx, double my) {
+    orig.mouseDown = false;
+
     switch(pending.operation) {
         case DRAGGING_POINTS:
         case DRAGGING_CONSTRAINT:

solvespace.h

@@ -669,11 +669,20 @@ public:
                             VectorFileWriter *out);
 
     static void MenuAnalyze(int id);
+
+    // Additional display stuff
     struct {
         SContour    path;
         hEntity     point;
     } traced;
     SEdgeList nakedEdges;
+    struct {
+        BYTE        *fromFile;
+        int         w, h;
+        int         rw, rh;
+        double      scale; // pixels per mm
+        Vector      origin;
+    } bgImage;
 
     void MarkGroupDirty(hGroup hg);
     void MarkGroupDirtyByEntity(hEntity he);

style.cpp

@@ -1,4 +1,5 @@
 #include "solvespace.h"
+#include <png.h>
 
 #define clamp01(x) (max(0, min(1, (x))))
 
@@ -108,6 +109,8 @@ void Style::LoadFactoryDefaults(void) {
         s->name.strcpy(CnfPrefixToName(d->cnfPrefix));
     }
     SS.backgroundColor = RGB(0, 0, 0);
+    if(SS.bgImage.fromFile) MemFree(SS.bgImage.fromFile);
+    SS.bgImage.fromFile = NULL;
 }
 
 void Style::FreezeDefaultStyles(void) {
@@ -327,6 +330,87 @@ void TextWindow::ScreenChangeBackgroundColor(int link, DWORD v) {
     SS.TW.edit.meaning = EDIT_BACKGROUND_COLOR;
 }
 
+static int RoundUpToPowerOfTwo(int v)
+{
+    int i;
+    for(i = 0; i < 31; i++) {
+        int vt = (1 << i);
+        if(vt >= v) {
+            return vt;
+        }
+    }
+    return 0;
+}
+
+void TextWindow::ScreenBackgroundImage(int link, DWORD v) {
+    if(SS.bgImage.fromFile) MemFree(SS.bgImage.fromFile);
+    SS.bgImage.fromFile = NULL;
+
+    if(link == 'l') {
+        FILE *f = NULL;
+        png_struct *png_ptr = NULL;
+        png_info *info_ptr = NULL;
+
+        char importFile[MAX_PATH] = "";
+        if(!GetOpenFile(importFile, PNG_EXT, PNG_PATTERN)) goto err;
+        f = fopen(importFile, "rb");
+        if(!f) goto err;
+
+        BYTE header[8];
+        fread(header, 1, 8, f);
+        if(png_sig_cmp(header, 0, 8)) goto err;
+
+        png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
+            NULL, NULL, NULL);
+        if(!png_ptr) goto err;
+
+        info_ptr = png_create_info_struct(png_ptr);
+        if(!info_ptr) goto err;
+
+        if(setjmp(png_jmpbuf(png_ptr))) goto err;
+
+        png_init_io(png_ptr, f);
+        png_set_sig_bytes(png_ptr, 8);
+
+        png_read_png(png_ptr, info_ptr,
+            PNG_TRANSFORM_EXPAND | PNG_TRANSFORM_STRIP_ALPHA, NULL);
+        
+        int w = info_ptr->width,
+            h = info_ptr->height;
+        BYTE **rows = png_get_rows(png_ptr, info_ptr);
+
+        // Round to next-highest powers of two, since the textures require
+        // that. And round up to 4, to guarantee DWORD alignment.
+        int rw = max(4, RoundUpToPowerOfTwo(w)),
+            rh = max(4, RoundUpToPowerOfTwo(h));
+
+        SS.bgImage.fromFile = (BYTE *)MemAlloc(rw*rh*3);
+        for(int i = 0; i < h; i++) {
+            memcpy(SS.bgImage.fromFile + ((h - 1) - i)*(rw*3), rows[i], w*3);
+        }
+        SS.bgImage.w      = w;
+        SS.bgImage.h      = h;
+        SS.bgImage.rw     = rw;
+        SS.bgImage.rh     = rh;
+        SS.bgImage.scale  = SS.GW.scale;
+        SS.bgImage.origin = SS.GW.offset.ScaledBy(-1);
+
+err:
+        if(png_ptr) png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+        if(f) fclose(f);
+    }
+    SS.later.showTW = true;
+}
+
+void TextWindow::ScreenChangeBackgroundImageScale(int link, DWORD v) {
+    char str[300];
+    sprintf(str, "%.3f",
+        (SS.viewUnits == SolveSpace::UNIT_MM) ? SS.bgImage.scale :
+                                                SS.bgImage.scale * 25.4);
+    SS.TW.edit.meaning = EDIT_BACKGROUND_IMG_SCALE;
+    ShowTextEditControl(v, 10, str);
+}
+
 void TextWindow::ShowListOfStyles(void) {
     Printf(true, "%Ft color  style-name");
 
@@ -354,6 +438,28 @@ void TextWindow::ShowListOfStyles(void) {
         REDf(rgb), GREENf(rgb), BLUEf(rgb),
         top[rows-1] + 2, &ScreenChangeBackgroundColor);
 
+    Printf(false, "");
+    Printf(false, "%Ft background bitmap image%E");
+    if(SS.bgImage.fromFile) {
+        Printf(false, "%Ba   %Ftwidth:%E %dpx   %Ftheight:%E %dpx",
+            SS.bgImage.w, SS.bgImage.h);
+        if(SS.viewUnits == SolveSpace::UNIT_MM) {
+            Printf(false, "   %Ftscale:%E %# px/mm %Fl%Ll%f%D[change]%E",
+                SS.bgImage.scale,
+                &ScreenChangeBackgroundImageScale, top[rows-1] + 2);
+        } else {
+            Printf(false, "   %Ftscale:%E %# px/inch %Fl%Ll%f%D[change]%E",
+                SS.bgImage.scale*25.4,
+                &ScreenChangeBackgroundImageScale, top[rows-1] + 2);
+        }
+        Printf(false, "%Ba   %Fl%Lc%fclear background image%E",
+            &ScreenBackgroundImage);
+    } else {
+        Printf(false, "%Ba   none - %Fl%Ll%fload background image%E",
+            &ScreenBackgroundImage);
+        Printf(false, "   (bottom left will be center of view)");
+    }
+
     Printf(false, "");
     Printf(false, "  %Fl%Ll%fload factory defaults%E",
         &ScreenLoadFactoryDefaultStyles);
@@ -575,6 +681,22 @@ bool TextWindow::EditControlDoneForStyles(char *str) {
             }
             break;
 
+        case EDIT_BACKGROUND_IMG_SCALE: {
+            Expr *e = Expr::From(str);
+            if(e) {
+                double ev = e->Eval();
+                if(ev < 0.001 || isnan(ev)) {
+                    Error("Scale must not be zero or negative!");
+                } else {
+                    SS.bgImage.scale =
+                        (SS.viewUnits == SolveSpace::UNIT_MM) ? ev :
+                                                                ev / 25.4;
+                }
+            } else {
+                Error("Not a valid number or expression: '%s'", str);
+            }
+            break;
+        }
         default: return false;
     }
     return true;

ui.h

@@ -101,6 +101,7 @@ public:
     static const int EDIT_STYLE_FILL_COLOR      = 54;
     static const int EDIT_STYLE_NAME            = 55;
     static const int EDIT_BACKGROUND_COLOR      = 56;
+    static const int EDIT_BACKGROUND_IMG_SCALE  = 57;
     struct {
         int         meaning;
         int         i;
@@ -160,6 +161,7 @@ public:
     static void ScreenCreateCustomStyle(int link, DWORD v);
     static void ScreenLoadFactoryDefaultStyles(int link, DWORD v);
     static void ScreenAssignSelectionToStyle(int link, DWORD v);
+    static void ScreenBackgroundImage(int link, DWORD v);
 
     static void ScreenShowConfiguration(int link, DWORD v);
     static void ScreenGoToWebsite(int link, DWORD v);
@@ -195,6 +197,7 @@ public:
     static void ScreenChangeStyleTextAngle(int link, DWORD v);
     static void ScreenChangeStyleColor(int link, DWORD v);
     static void ScreenChangeBackgroundColor(int link, DWORD v);
+    static void ScreenChangeBackgroundImageScale(int link, DWORD v);
 
     bool EditControlDoneForStyles(char *s);
     bool EditControlDoneForConfiguration(char *s);
@@ -322,6 +325,7 @@ public:
     Vector  projUp;
     double  scale;
     struct {
+        bool    mouseDown;
         Vector  offset;
         Vector  projRight;
         Vector  projUp;

wishlist.txt

@@ -1,6 +1,5 @@
 
 copy and paste
-background image
 associative entities from solid model, as a special group
 n*log(n) intersection finding