Fix max zoom limit so that the user can always turn on anti-aliasing.

diff --git a/gtkui/MainWindow.cpp b/gtkui/MainWindow.cpp
index a9ffb4b..472e898 100644 (file)
--- a/gtkui/MainWindow.cpp
+++ b/gtkui/MainWindow.cpp
@@ -132,11 +132,29 @@ void MainWindow::zoom_mechanics(enum Zoom type) {
        switch (type) {
        case ZOOM_IN:
                size /= ZOOM_FACTOR;
-               at_min_zoom = false;
+               at_min_zoom = at_max_zoom = false;
+               {
+                       /* Don't allow the user to zoom into somewhere we can't do an
+                        * antialiased plot.
+                        * I found that a limit of 2.0*rwidth*smallest_min didn't work,
+                        * presumably this is another precision issue. -wry */
+                       Fractal::Value d = fabsl(real(size)),
+                                       limit = 2.1 * rwidth * Fractal::Maths::smallest_min_pixel_size();
+                       if (d < limit) {
+                               size.real(limit);
+                               at_max_zoom = true;
+                       }
+                       d = fabsl(imag(size));
+                       limit = 2.1 * rheight * Fractal::Maths::smallest_min_pixel_size();
+                       if (d < limit) {
+                               size.imag(limit);
+                               at_max_zoom = true;
+                       }
+               }
                break;
        case ZOOM_OUT:
                size *= ZOOM_FACTOR;
-               at_min_zoom = false;
+               at_max_zoom = at_min_zoom = false;
                {
                        Fractal::Value d = real(size), lim = fractal->xmax - fractal->xmin;
                        if (d > lim) {
@@ -291,20 +309,12 @@ void MainWindow::do_plot(bool is_same_plot)
 
        double aspect;
 
-       aspectfix = at_max_zoom = false;
+       aspectfix = false;
        aspect = (double)rwidth / rheight;
        if (imag(size) * aspect != real(size)) {
                size.imag(real(size)/aspect);
                aspectfix=true;
        }
-       if (fabsl(real(size)/rwidth) <= Fractal::Maths::smallest_min_pixel_size()) {
-               size.real(Fractal::Maths::smallest_min_pixel_size()*rwidth);
-               at_max_zoom = true;
-       }
-       if (fabsl(imag(size)/rheight) <= Fractal::Maths::smallest_min_pixel_size()) {
-               size.imag(Fractal::Maths::smallest_min_pixel_size()*rheight);
-               at_max_zoom = true;
-       }
 
        // N.B. This (gtk/gdk lib calls from non-main thread) will not work at all on win32; will need to refactor if I ever port.
        gettimeofday(&plot_tv_start,0);