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- prevent zooming in too much

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- debugging syntax changes


git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@3101 c8812cc2-4d05-0410-92ff-de0c093fc19c
This commit is contained in:
g_j_m 2005-04-08 23:40:45 +00:00
parent 7bcd58f934
commit 9db8708fa3
1 changed files with 51 additions and 25 deletions
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72
src/qgsmapcanvas.cpp
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@ -621,13 +621,32 @@ void QgsMapCanvas::render(QPaintDevice * theQPaintDevice)
{
// Don't allow zooms where the current extent is so small that it
// can't be accurately represented using a double (which is what
// currentExtent uses). Excluding 0 avoids an infinite loop when
// rendering to a new canvas.
static const double minExtent = 1e-12;
if ((mCanvasProperties->currentExtent.width() > 0 &&
mCanvasProperties->currentExtent.width() < minExtent) ||
(mCanvasProperties->currentExtent.height() > 0 &&
mCanvasProperties->currentExtent.height() < minExtent))
// currentExtent uses). Excluding 0 avoids a divide by zero and an
// infinite loop when rendering to a new canvas. Excluding extents
// greater than 1 avoids doing unnecessary calculations.
// The scheme is to compare the width against the mean x coordinate
// (and height against mean y coordinate) and only allow zooms where
// the ratio indicates that there is more than about 12 significant
// figures (there are about 16 significant figures in a double).
if (mCanvasProperties->currentExtent.width() > 0 &&
mCanvasProperties->currentExtent.height() > 0 &&
mCanvasProperties->currentExtent.width() < 1 &&
mCanvasProperties->currentExtent.height() < 1)
{
QgsRect extent = mCanvasProperties->currentExtent;
// Use abs() on the extent to avoid the case where the extent is
// symmetrical about 0.
double xMean = (std::abs(extent.xMin()) + std::abs(extent.xMax())) * 0.5;
double yMean = (std::abs(extent.yMin()) + std::abs(extent.yMax())) * 0.5;
double xRange = extent.width() / xMean;
double yRange = extent.height() / yMean;
static const double minProportion = 1e-12;
if (xRange < minProportion || yRange < minProportion)
{
// Go back to the previous extent
mCanvasProperties->currentExtent =
@ -635,6 +654,7 @@ void QgsMapCanvas::render(QPaintDevice * theQPaintDevice)
repaint();
return;
}
}
#ifdef QGISDEBUG
QString msg = mCanvasProperties->frozen ? "frozen" : "thawed";
@ -700,7 +720,8 @@ void QgsMapCanvas::render(QPaintDevice * theQPaintDevice)
{
dymin = mCanvasProperties->currentExtent.yMin();
dymax = mCanvasProperties->currentExtent.yMax();
whitespace = ((myWidth * mCanvasProperties->m_mupp) - mCanvasProperties->currentExtent.width()) / 2;
whitespace = ((myWidth * mCanvasProperties->m_mupp) -
mCanvasProperties->currentExtent.width()) / 2;
dxmin = mCanvasProperties->currentExtent.xMin() - whitespace;
dxmax = mCanvasProperties->currentExtent.xMax() + whitespace;
}
@ -708,7 +729,8 @@ void QgsMapCanvas::render(QPaintDevice * theQPaintDevice)
{
dxmin = mCanvasProperties->currentExtent.xMin();
dxmax = mCanvasProperties->currentExtent.xMax();
whitespace = ((myHeight * mCanvasProperties->m_mupp) - mCanvasProperties->currentExtent.height()) / 2;
whitespace = ((myHeight * mCanvasProperties->m_mupp) -
mCanvasProperties->currentExtent.height()) / 2;
dymin = mCanvasProperties->currentExtent.yMin() - whitespace;
dymax = mCanvasProperties->currentExtent.yMax() + whitespace;
}
@ -774,11 +796,13 @@ void QgsMapCanvas::render(QPaintDevice * theQPaintDevice)
{
// QgsDatabaseLayer *dbl = (QgsDatabaseLayer *)&ml;
#ifdef QGISDEBUG
std::cout << "QgsMapCanvas::render: Rendering layer " << ml->name() << std::endl;
std::cout << "Layer minscale " << ml->minScale() << ", maxscale " << ml->maxScale()
<< ". Scale dep. visibility enabled? " << ml->scaleBasedVisibility()
std::cout << "QgsMapCanvas::render: Rendering layer " << ml->name() << '\n'
<< "Layer minscale " << ml->minScale()
<< ", maxscale " << ml->maxScale() << '\n'
<< ". Scale dep. visibility enabled? "
<< ml->scaleBasedVisibility() << '\n'
<< "Input extent: " << ml->extent().stringRep()
<< std::endl;
std::cout << "Input extent: " << ml->extent().stringRep() << std::endl;
try
{
std::cout << "Transformed extent"
@ -924,19 +948,21 @@ void QgsMapCanvas::currentScale(int thePrecision)
std::cout << "---------- Current Scale --------------- " << std::endl;
std::cout << "------------------------------------------ " << std::endl;
std::cout << "Current extent is " <<
mCanvasProperties->currentExtent.stringRep() << std::endl;
std::cout << "MuppX is: " <<
muppX << "\nMuppY is: " << muppY << std::endl;
std::cout << "Canvas width: " << width() << ", height: " << height() << std::endl;
std::cout << "Extent width: " << mCanvasProperties->currentExtent.width() << ", height: "
std::cout << "Current extent is "
<< mCanvasProperties->currentExtent.stringRep() << std::endl;
std::cout << "MuppX is: " << muppX << "\n"
<< "MuppY is: " << muppY << std::endl;
std::cout << "Canvas width: " << width()
<< ", height: " << height() << std::endl;
std::cout << "Extent width: "
<< mCanvasProperties->currentExtent.width() << ", height: "
<< mCanvasProperties->currentExtent.height() << std::endl;
QPaintDeviceMetrics pdm(this);
std::cout << "dpiX " << pdm.logicalDpiX() << ", dpiY " <<
pdm.logicalDpiY() << std::endl;
std::cout << "widthMM " << pdm.widthMM() << ", heightMM "
<< pdm.heightMM() << std::endl;
std::cout << "dpiX " << pdm.logicalDpiX()
<< ", dpiY " << pdm.logicalDpiY() << std::endl;
std::cout << "widthMM " << pdm.widthMM()
<< ", heightMM " << pdm.heightMM() << std::endl;
#endif
// calculate the actual extent of the mapCanvas